Yesterday, Rush Limbaugh aired as a replacement for Gary Burbank on XM Satellite Radio's WLW (ch 173).
It looks like WLW is simply doing a rotating set of "surprise guest hosts" or something of that sort, and Rush was yesterday's guest host. But that's not the point. The point is that they were able to broadcast Limbaugh's program on XM. Something that I thought was never going to happen.
Let the speculation ensue.
A couple years ago, Limbaugh directly addressed the question of making the jump to satellite radio, succinctly stating that he would "cannibalize" himself if he went to Sirius or XM. With a weekly minimum audience of roughly 14 million listeners, Limbaugh is by far the biggest talk radio host in the country.
WLW is broadcast on XM as part of their contractual obligation to Clear Channel (which, incidentally, I believe is set to expire in June of this year). And Clear Channel owns Premiere Radio Networks, which syndicates The Rush Limbaugh Show on some 600 stations nationwide.
There's some additional discussion at Radio-Info