I've looked into TBB but never used it in a project. I saw no advantages (for my purposes) over ZThread. A brief and somewhat dated overview can be found here.
It's fairly complete with several thread dispatch options, all the usual synchronization classes and a very handy exception based thread "interrupt" mechanism . It's easily extendable, well written and documented. I've used it on 20+ projects.
It also plays nice with any *NIX that supports POSIX threads as well as Windows.
Worth a look.
