How long are older versions of Android supported
When you're about to start Android app development, you should not stick to the 'old' Gingerbread version.

Of course you'll still use many things introduced in Android 2.3 and older, so most of the tutorials still work. This is very important, because even if you target API level 15, you need to care about backward compatibility!

As an unexperienced developer, later Android versions help you writing better apps. For example Android 3+ applications forces developers to use AsyncTasks for networking services, so your application does not freeze on network issues.