This happened to my Motorola Droid tonight. my friend got a hold of my phone and
tried random pattern to unlock my phone. needless to say, my phone got locked out. i
entered my gmail address and password but failed.
here's the procedure to unlock without hard reset:
1) create a new gmail account on the computer.
2) call your cell phone with a different phone.
3) answer your cell phone then hit the back button and it will take you to the home
4) turn on wifi so it can do data and voice at the same time (remember that the phone
is still connected)
5) go to Settings -> Location & Security and disable lock pattern (you'll need to
enter to correct pattern previously set)
6) go to Settings -> Accounts & Sync and click "Add Account" and add your newly
created Gmail account.
7) hang up the phone.
8) turn the phone back on, at the lockout screen, enter your new Gmail account info
and it should let you back in
9) once the phone is unlocked, you can go in setting and remove the newly added Gmail
account and keep the old one.