Imagination paid a lot of money for MIPS, and they are definitely doing the right thing releasing a low cost hobby board based on their CPU/GFX IP. But the board is around the same price as an equivalent ARM board, but with less mature developer tools and far less investment (I wouldn't expect to see a MIPS desktop/server capable board any time soon).
I find myself tempted to get one... But there are better ARM boards for the money.
-edit- The HummingBoard is very exciting :-)