I have carried a five inch tablet with me everywhere for the last three years.
Its made by Dell, is currently running Android 2.2 although I could get 2.3. Its called the Streak and its also a phone.
Back in the Windows Mobile Five days, HTC had one of those with a five inch screen and built in phone called the Advantage.
The five inch tablet market is nothing new in any way and it has always generated interest...its just that the prices had to drop out of the stratosphere before many people would buy.