I picked up a G1 on a pay-as-you-go contract in the T-mobile store in Alt-Tegel (Northwest Berlin) earlier this morning. There's one GIANT problem with getting the phone this way that I'm looking all over for a good solution for still.
The problem is that the phone is sending some kind of communication every 5 minutes - even if you turn off google synchronization. At 9 (euro)cents per instance that adds up to 9,460 euros per year, just to have the phone idle. That's about 15,000 $/yr, for my fellow Americans, at current exchange rate.
There's a poor hack around the problem: Installing "apndroid" from the Android Market allows you to turn off and on ALL non-voice communication by the phone with a single click. So now you're not having your SIM credit emptied continuously; only when you forget to click that tech back off after each use. And you have to click it on before each use. And your expensive smart-phone is stupider than a 10-euro throwaway phone most of the time, because you turned off texts and everything else other than for select moments.
I'm eager to hear if anyone knows a better way around this problem. I've been pretty much sitting in a coffeehouse scouring the web and posting to discussions like these since I got the phone, and nothing yet.