A valid point. The answer, of course, is that we should shun the 'media-chosen' Republican nominee with extreme prejudice.
As to Palin, the media is doing everything in their power to prevent her from being chosen as the Republican nominee for 2012. In her case, she's actually got the necessary level of support from the voters to be chosen, which is how it should be.
The MSM is certainly covering her to the nth degree, with ill intent in 80% of the cases. However, she is on Fox constantly, many of the right talking heads love her and promote her (Rush, Hannity, etc), and the AmSpec, Human Events, Townhall - the conservative electronic media - by and large cover her far more than the others.
Last time out Rush/Levin/FR were pushing Fred (then Mitt), Medved was pushing McCain, Hannity was pushing Rudy, Hewitt was pushing Mitt, the evangelicals were pushing Huck, etc etc.