There is a First Posts beta review task now. That one has currently about 34K posts. What stumps me a bit is that the old First Questions queue had over 300k posts in it yesterday. So what happend to the difference?
The old /review page was based on reputation, and could actually contain multiple posts from the same person. At the same time, it excluded true first posts from folks who passed the reputation threshold by some other means. IIRC, it was actually based on a 10K tool that existed previously, the more accurately named, "New Posts by New Users".
The new queue focuses specifically on the very first post made by a member of the site. The only exception right now is that posts older than 30 days are excluded - otherwise, everything else is fair game. If you show up and post a dozen answers on your first day, the first of these will still be in the queue - but the rest won't be.
The up-side of this is that it should be much more useful as a means of introducing new users to the site: rather than being clogged with posts from prolific but mediocre writers, everyone signing up gets one shot at fame.
The down-side is probably that it's less useful for highlighting crap. But at this point, we have better ways of handling that.