I'm running PerlCE on my iPaq and it seems to work well. I keep this build on a storage card. IO::Socket, Win32::Serial, Win32::API and Win32::OLE are in there, and some modules can be brought over. I haven't found much doco on the net for api calls on ce, but I haven't looked very hard either.

I've only really used PerlCE to run a while loop and feed text into the flite program, but I'm planning on using it to read data from my gps, log it, then make announcements based on location. (flite is the festival lite engine ported to ce, you can use it to make your pda talk, available on the same site.)