it's funny, you hear from old white Republitard guys that the Palin pick was expected to pull in a lot of female votes (and they're confused why it didn't), but I think it pretty much alienated any that were on the fence.
it was so transparent, and Palin was such an idiot, I know a few told me they found it insulting. Not many woman identify with her, and the ones that actually like her, or respect her "career" would vote GOP if they nominated Charles Manson, so it didn't certainly didn't help McCain's campaign at all.
Still to this day I find that when the topic of Sarah Palin comes up in conversation, and there are educated females around, the mere mention of her name provokes a lot of hostility... you don't really see that from any other VP pick in history.
Basically, if the RNC didn't want McCain to be president, they couldn't have picked a better VP for him.