In biteSMS's settings there is an option to change the icon. Change it to iMessage icon. Not sure if thats what your problem was.
That didn't do it. I think Handcent really fucked something up. I'm guessing it may have something to do with clicking an option in it oreviously to make it the default messaging program. I unclicked it at some point and have even reinstalled it and toggled it back and forth, to no avail.