libspe vs. libspe2? What's the difference?

I've been doing some experiments with the Cell processor in a PS3 that I have sitting around and I've run across an issue. It appears that there are two versions of the main SPE management library, libspe and libspe2. What is the difference between them? From what I can tell the main difference is that in libspe they rolled their own threading code, whereas in libspe2 you have to integrate the libspe with the pthreads library to achieve multiple threads. Is there any reason that one is better than the other? What is being gained/lossed/changed between the two?

From stackoverflow

• I don't know about that stuff, I don't see those libraries in the Sony-provided SDK (although I couldn't comment if I had them!).

  Have you checked out IBM's site for information? http://www.ibm.com/developerworks/power/cell/

• Alright, so it looks like libspe2 is the way to go. What I noted above about threading is pretty much the main difference, libspe2 provides a much more flexible threading model. Also, libspe is deprecated as of SDK 2.1 and 3.1 is the current version, so starting any new projects with libspe is probably a bad idea.

  There is a good article with examples on the IBM site here.