I would love to try out grand central dispatch, but all I have to develop on is an Ubuntu workstation. Is libdispatch, and the blocks extension to c/obj-c etc... available on linux? If so, how do I get them?
You may need to use the LLVM Clang (available on Ubuntu) compiler to get blocks at this time (I don't think this is available in gcc yet, but I haven't been keeping up with gcc, so I could be wrong.)
There are efforts underway to port libdispatch (home for the open source libdispatch) to Linux. Most of the effort seems to be on Debian so far, but some on other distributions, too. See these discussion threads: