After more thoughts it seems that building an email newsletter about Android games might be the way to go. >10k is a good initial userbase. The newsletter could later become a promotion channel for developers and I can include that into the multiplayer framework package too.
Two main questions for me right now are the frequency (weekly or biweekly maybe(?)) and the content of the newsletter. Android games related topics is an interesting niche - and a heavily expanding one if the current growth of Android continues. Any suggestions what I could write about? Perhaps game reviews and what's going on in the Android game scene in general? I think there will be a couple of interesting things coming up with C2DM [1], where the private beta is currently starting (got an invite today - for the multiplayer engine! :).
Maybe I could also partner with existing Android app / game / review websites.
Ideas and advices are greatly appreciated!
[1] http://code.google.com/android/c2dm/index.html (Google's cloud-to-device messaging, introduced in Android 2.2)