Here's an easy one. MJB and Big Boi with Something's Gotta Give.
The Dream and Young Jeezy's "I Luv Your Girl" is only here because of the first lyrics.
Of course "Yes We Can" which is just Will.i.am and some other celebrities singing along with Obama.
"Black Republicans" by Weezy and Juelz Santana
Not as much politically themed, but I'm sure a lot of us will be watching the news tonight, so Nas' "Sly Fox" can get a mention.
Sorry I couldn't find any about McCain. I did find some lame thing about Huckabee but it wasn't really good at all.