According to CNET report, Android 3.0 won't be open source. Google said Android 3.0 is not ready to customize yet. I am not agree with Google. Maybe, changing Android 3.0 will be a bad idea. It won't work as well as its design. But philosophy of opensource is diversity. Opensource community will develop a number of ways to use Android 3.0. They can be good or bad. Definitely, they will be never to be think of inside Google.

Reference:
Google not ready to share Honeycomb source code (CNET)