Reading over the A51 proposals, I see a proposal for a sexuality Q&A site (cough "sackoverflow" cough ). I don't know if I would particularily like Careers2.0 to link up a potential employer or customer with my contribution in threads regarding sexuality.
We've talked a lot about this one on the Stack Exchange Community Team, and we have plenty of time before the Sexuality proposal is likely to see a private beta in which to hammer out the details. It is clear to us that there will need to be some separation between the Sexuality site and the network at large -- for example, non-PG13 question titles shouldn't appear in the "hot question" box at the top of other sites. The extent of the separation and the implementation details are still up for grabs, but don't worry, we're thinking the same things you are.
This isn't to say that we'll be able to magically keep anyone from noticing your participation if they are looking for it, and if you use your usual nickname and/or associate your accounts. We're just not going to advertise it.
You can whip up a new OpenID and create an unlinked account on any new site pretty easily. Heck, once it moves past the closed beta, you don't even need to log in at all...
Also, I have high hopes that ol' Hedge can whip up an even more opaque name for the thing 'fore it actually gets out the door.