That's strange. The factory restore should have removed the pattern lock. And, to be certain I've just tried it on my Galaxy S which did remove the pattern lock. Wiping the cache partition won't remove the pattern lock.
Can I suggest you try performing the factory restore again from recovery mode. From past experience I've known the factory restore to fail sometimes and retrying should do the trick. When the phone reboots, the first screen should be the language selection screen. If not, there is something obviously wrong and we may have to resort to flashing a new firmware. Not as difficult as it sounds.
All the best.