<p>I have a <code>T-Mobile G1</code> and I'm going to download the developer SDK and see if I can create a few simple apps for my phone.  If you've done similar development, please answer below and tell me about your experience.  Please share any links you found especially useful.</p>

I started from here
http://code.google.com/android/kb/commontasks.html
I got my environment and emulator up and running within about 15 minutes.
First impressions are its fun to work with.
Paul