Android: For all practical purposes, which api version should I be targeting

Title says it mostly...

While it would be nice to be able to cover 90%+ of devices in use now, if it starts to complicate things, I think, focusing on devices being released now and soon clearly has priority.

Bonus points, on guidelines to set project settings and 开发者_如何学Cemulator to be in sync and without warnings.

See the Android Dashboard for stats on API usage and trends: http://developer.android.com/resources/dashboard/platform-versions.html

(As of May 2011, it looks like targeting 2.1 and 2.2 covers about 90%, but obviously this will change.)