According to the Heisman piece on the front of ESPN's college football page, Drew Henson had originally committed to play for Florida State. He switched his commitment to Michigan only after Chris Weinke decided to leave professional baseball to play quarterback for the Seminoles. Henson didn't want to compete for playing time with Weinke, so he chose Ann Arbor instead.
"[Weinke] called and asked if he could come back," Bowden said. "He was about ready to give up baseball because he wasn't making the progress he wanted to make. He wanted to know if we'd take him back." The Seminoles wanted Weinke back, but highly regarded quarterback Drew Henson of Brighton, Mich., had already committed to play for FSU. "He wasn't going to come if Weinke came," Bowden said. "We had to decide if we wanted Weinke or [Henson]. I know my vote was to bring Weinke back."


I don't remember this happening. I'm pretty sure that Henson committed to Lloyd before his senior year with the agreement that he wouldn't recruit any other QBs that year.
Of course, this is before recruiting coverage took off so it could have happened and we never knew about it.