Glyn has made the case for respecting her wishes. After all, while some have noted her "transition" as an effect of white privilege, her adoption of certain ethnic tropes as cultural appropriation (of which there is a long and inglorious history), and her stance as a way of muddying the persistence of racial inequalities in the US; analogous arguments around transsexualism have increasingly little purchase in feminist and progressive circles. Trans people still face an awful lot of crap, but it seems the long-term tendency is toward greater cultural acceptance - not least because the efforts of trans activists and their allies. That said, I don't think the comparison stacks up.
As a socialist, I believe in individual liberty. Everyone should have the right to live the life they wish to, provided that it does not bring harm to others (hence why socialism is consistent liberalism, among other things). If people want to undertake body modification, then it's up to them. In a future world where inequalities are no longer a systematic property of the societies we live in, then if someone wants to change their skin colour and/or adopt the traditions and styles of dress associated with a particular ethnic group, it's a matter for them and them alone. Yet doing that now, while a matter of individual liberty, takes place in a context of racially charged politics. Because that is the situation, and because Dolezal herself elected to place herself in the public view, regardless of her subjectivity and self-identification her transracialism was always going to cook up a storm.
To understand this context, one must pick up on two contradictory trends in US African-American politics. The first of these is the so-called post-black movement. Perhaps 'movement' is pushing it, trend is more apposite. Readers familiar with "post-feminist" (as opposed to postmodern feminism) arguments can guess what this means: that the key battles between racism have been won. All that is left is a mopping up operation and a gradual move of black people outwards into mainstream culture.
For example, the suite of novels by Percival Everett - Glyph (1999), Erasure (2001), American Desert (2004), and I Am Not Sidney Poitier (2009). Erasure, which is the most complex but funniest of his novels outrageously but knowingly rips off canonical African-American literature (Native Son, Invisible Man, all of James Baldwin's stuff). It revolves around the adventures of a middle aged, middle class literature professor sick of having his literary novels typecast as "black fiction" when they're nothing of the sort, but are so-labelled because of his ethnicity. After the literary establishment goes gaga over a particularly egregious novel by the name of We Lives In Da Ghetto, the protagonist writes an overtly satirical but anonymously-published novel sending up all the ghetto tropes. Yet it is taken seriously and feted as a master werk of African-American fiction, and mayhem ensues. What Everett demonstrates is the frustration of being hemmed in, of black intellectuals being only "allowed" to comment on a narrow range of issues specific to African-Americans, a range that the black cultural establishment have contrived to keep for themselves.
If Erasure articulates the post-black sensibility while, ironically, playfully embedding itself rather heavily in the black literary canon, the cultural trend is real enough. What better exemplar is there of the post-black than Barack Obama, a president for whom "blackness" is inessential? Or of Kanye West, tedious rapper-turned Kardashian? Or of Snoop Doggy Dogg, the "gangsta"-cum-reality TV clown? Or the spread of African-American characters in comic books, including the recent redefinition of Spider-Man as a black teenager? According to Ytasha Womack in her Post-Black (2010), these are examples of African-Americans moving outwards. They're not necessarily rejecting their heritage - indeed, she notes it wouldn't have been possible without the civil rights movement and generations of black activism, but as an identity location it's constraining. Now there are more opportunities available it's possible to move beyond "blackness". Therefore the post-black is a liberal aspiration, a trend, and, for some, a reality. It looks forward to a time when race no longer matters, where ethnicity is an attribute one can shed or adopt. Rather than being transracial, in this sense perhaps Dolezal can be considered the personification of the post-black, of the separation of race and ethnicity (which was always a cultural contrivance anyway).
The other trend, however, is a re-embodiment of blackness or, rather, the attempts racism makes to renew and perpetuate itself. When we're talking about the racial politics of any society, we're discussing how certain bodies are culturally marked and unmarked. The post-black counts for nothing as far as racism is concerned. American racists fearful of the Anti-Christ in the White House have noted the colour of Obama's skin and hate accordingly. The appalling recordings of US cop murder and assault that flash around the world on an almost weekly basis remind us there are still very powerful institutions in the States who are systematically racist and virtually untouchable by the justice system - unlike Britain. Hence more than anything, it's not because of "choice" that a distinctive black culture exists but structural inequality and intentionally discriminatory practices. It was forever thus. In this context of renewed proof that the materiality of the body matters, and with it a similar strengthening of black-based solidarity and resistance (see Ferguson and Baltimore, for example), the sideshow of Dolezal's transracialism can and has been felt quite strongly. You don't have to possess sensitive political antennae to see how this can be construed as an act of cultural appropriation of blackness; just a sense of history.
There is also another wider context to this. When the Dolezal news broke it was seized upon with alacrity by right wingers. Partly because they found it funny, but here they had a political stick to beat white people's solidarity with anti-racist causes and campaigns. The NAACP, for instance, does allow caucasian members to hold office, but in Dolezal they have found someone who can make active anti-racists who happen to be white appear, well, a little bit odd and their concerns the province of the mad. For extremists it's another way to dehumanise their white opponents as self-hating too.
What then is to be done? Absolutely nothing. If Dolezal wants to carry on as she has been doing, it's a matter for her. She has - rightly - resigned her NAACP positions and given the huge global media spotlight on her is likely undergoing more than a touch of soul-searching. However, because of the context, which she would not be unfamiliar with, she will remain a talking point. Dolezal knows US politics cannot escape race, and ultimately neither can her transracialism.