A recent industry rumor indicates that Google intends to make the Android Ice Cream OS a combination of the Android phone, tablet and GoogleTV OS's. For some time, they have wanted to create a single project for all three code-bases, and the next OS, Ice Cream, will merge these together. Furthermore, the same 'intel' suggests that Google intends to officially announce this at Google IO in May. Additional industry speculation suggests this is the primary reason why Google delayed the source code release of Honeycomb. Also it is because Google wants to further reduce fragmentation and is a an initial push to make cross-platform apps easier to create for GoogleTV developers in the future.
Source: Android.net via SlashGear