Have the same thing on mine today. Did a reboot on the phone this morning, and when I powered up, said I had a couple updates available from the market. I clicked it, I have TWO in the market, under My Apps. Maps, and Youtube. That's it. No idea why it doesn't show the rest (which are obviously working). No login prompt, everything else works as it should. Weird.
edit: found it. Apparently, there's now a way to add multiple Google Accounts lol. I noticed it had added a 3nd google account for me...
Go to the Market, main page, hit your Settings button, go to Accounts, and pick the correct one. Should be there. Not sure why my 2nd one is even listed, was totally weird. It's almost as if it took my Yahoo account, and made a "new" google account with it. Once I selected the correct one though, it shows all.