I've not tried cross-compiling yet, but my onboard compile just takes removing all previously compiled *.o files, ensuring all dependencies are filled, then using 'make'.

EDIT: I've been playing around with wireshark. I've found grooveshark packets when using the browser app and can identify individual song downloads. Still not sure how to find the correct client version string, but I need to read into it more.

I'm installing the virtualbox of the maemo sdk and will attempt to build one of the older versions. I'll probably try building for ubuntu as well just to test. I'll let you know when I at least get it to compile on something other than my pandora.