Android :: Preferred Way To Support Multiple Android OS Versions?

I have a few scenarios where I guess I am not alone with. There is no easy solution but this has to be on top of the list I think.

1. Suppose you have an application that is compiled with 1.5 and is working fine even if started on a 1.6 device. But you now want to support other resolutions, so you need to compile with 1.6. Problem: If I recompile and publish the new apk, the 1.5 users want see my applications. Users already downloaded my application can not upgrade. (will there be a "new version" available shown to them in the market?)

2. Lets say your application works fine on 1.5 and 1.6 and you decided to publish your application twice with different package names. "MyApplication 1.5" and "MyApplication 1.6" for example. Problem: The user upgrading from a older version does not know that there is a new version, because you published a new Application. You can write it into the description and tell the user to download the 1.6 version but many users might not read that Settings from the other application are lost. Your downloads are split into two applications, so you might not make it into the top ranks that easy . You might even need to publish 4 applications if you have a light and a paid version.

3. Now 2.0 SDK is available and you want to add multi touch features or any other new stuff for all 2.0 users. Problem: The above problems are getting even worse. There is no way to easily upload multiple apks for the same application. Having to rename the package is also not making this better. Every time svn freaks out and marks everything as new. Sharing code between versions is difficult because of that.

I don't know if its just "3" (provider in Austria), but I still have not received an official update to 1.6. Testing on the real device is not possible with a 1.6 image if you don't want to root your phone and update the rom manually. 2.0 will be on some devices soon, so there is definitely a need to support all 3 versions. There should be a faster update cycle for the users or a slower update of new versions meaning bigger steps. or We get an easier way to support multiple versions. This also means we need a way to know how many actual devices with version 1.5 / 1.6 / 2.0 are already sold and/or upgraded. If i know that 1.5 is only on about 5% of the devices left, then I can just stop supporting that version and upgrade.