I have looked at http://developer.android.com/resources/dashboard/platform-versions.html

2.1 : 27.2%
2.2 : 63.9%
2.3 : 0.8%
2.3.3 : 1.7%
3.0 : 0.2%
I am pretty sure I will use Android 2.1 as my version, covering almost 94% of current users. When I go to set up an android application in eclipse, I see this screen

The documentation says
Min SDK Version
This value specifies
the minimum API Level required by your
application.
What does that mean? Does that mean I can pick 2.3 for my build target, but select 7 as the min sdk version and have all devices running 2.1 supported?
I found a similar post ( Android Min SDK Version vs. Target SDK Version ). Here’s part of the answer:
An integer designating the minimum API Level required for the application to run. The Android system will prevent the user from installing the application if the system’s API Level is lower than the value specified in this attribute. You should always declare this attribute.
An integer designating the API Level that the application is targetting.