<p>Intel's <a href="http://www.threadingbuildingblocks.org/" rel="noreferrer">Threading Building Blocks (TBB)</a> open source library looks really interesting.  Even though there's even an <a href="http://oreilly.com/catalog/9780596514808/" rel="noreferrer">O'Reilly Book</a> about the subject I don't hear about a lot of people using it.  I'm interested in using it for some multi-level parallel applications (MPI + threads) in Unix (Mac, Linux, etc.) environments.  For what it's worth, I'm interested in high performance computing / numerical methods kinds of applications.</p>

<p>Does anyone have experiences with TBB?  Does it work well?  Is it fairly portable (including GCC and other compilers)?  Does the paradigm work well for programs you've written?  Are there other libraries I should look into?</p>

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.