Spiff,
If you've paid a lot of money for your ticket and it's cheaper for the airline to reaccomdate you onto another airline, they may be reluctant to give you a refund. However, this is VERY rare. It's only happened to me one time: AA rebooked me onto DL despite my protestes.
<font face="Verdana, Arial, Helvetica, sans-serif" size="2">Originally posted by Spiff:
Wait a minute... if the alternate carrier is not acceptable to you, aren't you entitled to a refund? There is almost no way I would let AA or DL put me onto CO and/or some kind of RJ in lieu of a mainline aircraft.</font>