Here's another rumor from Digitimes:
Talking with upstream component makers, the analyst pointed out that Nokia has already completed about 100 engineering samples ready for testing. The tablet PC's panel size will be either 7- or 9-inch and manufactured by Foxconn International Holdings (FIH), the Hong Kong-listed handset subsidiary of Foxconn Electronics (Hon Hai Precision Industry), the analyst noted.
My opinion on this is mixed. Yes, I think Nokia is working on a tablet. But, I don't think they're going to release it. The tablet market is going to be quite crowded by late summer, and I expect Nokia to cut their losses and shelve the prototype.
But if they were working on a tablet, the UI might look something like this: