Fortunately for developers Amazon hasn't forked the OS too much. The APIs for the latest release are the ICS APIs which is OK since most devs will still be targeting Froyo or Gingerbread for another year or so. The only problem is if you use some of the Google APIs, mainly Maps, in which case you'll have to get clever, either with reflection or your build system, to include Amazon's maps in your app.

If Amazon ever tries to do a major fork at the API level we'll be in trouble, but they have shown no sign of that as of yet.