I'm starting on the Hildon C++ bindings for Nokia. Setting up the development environment was really easy with the detailed instructions. I used the scratchbox 0.9.8.5 version via the debian apt-get source, and it worked fine on Ubuntu Breezy.
Compared to emulators I've used for mobile phone work, this is easy thanks to a fakeroot shell and X-Windows. The N770 environment just runs in a second nested X server. And because it's a real linux system, with shared libraries and real processes, instead of a lump of statically-compiled hacks, you can start and stop programs individually (run-standalone.sh yourapp), just like a real computer, and actually debug/interact with them properly. You can't understand how nice this is unless you've experienced the tedious crap I've used in the past. I haven't developed for Nokia phones, but I bet it isn't this good.