I'm having the same issue. After I delete all the SMS's, the same two still appear on the today screen. Also, when I get a new sms, it does appears on the today screen, then when I view the message, and go back to the today screen, the latest message no longer appears, and its the two previous stuck messages are still there, even if they were deleted from the phone.
I've only had the phone 4 days now, and for the 1st 2 days it worked fine, the last 2 I've got these two stuck SMS's. I rebooted and it was still there, ended up pulling the battery and they disappeared, but just 2 more sms's will get stuck again.