I recognize that were McCain to select Palin as his Veep it disrupts the Obama Lacks Foreign Policy Experience” talking point, but I was never thought that argument was all that powerful. Palin probably has as much foreign affairs experience as did our current President when he was elected (and as much as Carter, Reagan, or Clinton — and as much as some of the other Veep prospects some conservatives promoted, e.g., Jindal). All this is just to say judgment is more important than experience — it just so happens that Obama lacks both. Many State Department hands have a wealth of relevant experience, but would promote awful foreign policies, and many folks with relatively limited experience do just fine.
Anyhow, this is probably all moot. While I would have loved to see Palin on the ticket, it does not look like that will happen.