Work? I tried to evaluate it a while ago (FC15 beta, so it wasn't THAT long ago) but I hit kernel panic whenever I try to put load on it (a heavily multi-threaded program). The redhat guys I chatted with on IRC were really helpful and fixed some issues (but not all), but I didn't have time to pursuit further.
A coworker ported our code to Solaris and dtrace hasn't had a problem with it yet. The situation is not ideal as we actually ship on Linux, but we only use tracing internally now so it's not too big of a deal.