Fudd.
To add to the above- Anchor Steam or Liberty Ale.
Absolutely not just because of the name: Stone Brewery’s Arrogant Bastard. 
My father taught me to keep the bottle and bag for years. He would refill it with Vat 69 for BYOB occasions. No one seemed to ever notice.
That was my answer. If it was good enough for my grandpa to drink while sitting in the garage, it’s good enough for the president of the United States!
Come to think of it, they should all sit in the White House garage while drinking it. Or maybe in the alley.
Yuengling.
“Arrogant Bastard Ale”.
Then sit back and be amused for days as the pundits try to decide who I was calling a bastard.
(Bah! I didn’t see that runner pat beat me to it.)
It would be worth Obama chosing a Mexican beer just to make Lou Dobbs pop a blood vessel.
Of course, even better would be Senator Keg Lager (AKA “Obama Beer”) from Kenya. That would make birther heads pop all over the country.
Then they’ll have to listen to the White Sox play the Yankees, and then Crowley will get all agitated because he has to be a Red Sox man. Gates might be too, but he was born in West Virginia, not too far from Pittsburgh.
FYI, I was just checking the ownership of Sam Adam Beer, and was suprised to read in Wikipedia that with the Belgian takeover of Anheuser-Busch that the Boston Beer Company (parent of Sam Adams beer) is the largest American-owned brewery.
Bud Light? 
That makes me sad; now I can’t vote for Obama in '08.
Sam Adams would be a great choice for all the reasons the OP mentioned, but if it were me, I’d go with a good Oregon beer to give some props to my home state and its excellent, excellent breweries. Truly, Oregon is a beer wonderland. I’d probably choose a Widmer Hefeweizen, since that’s the label that most people are gonna be familiar with. I do love me some Bridgeport IPA or Deschutes Black Butte Porter, though.
Then again, if I were Obama, I’d move the White House to Portland, soooo…
Rolling Rock in pony bottles in a tub of ice. Menu would be ribs on the grill.
A hometown brew from Chicago’s own Goose Island. Probably a 312 or Pere Jacques. If it was cold out, a Bourbon County Stout.
My issue is not so much the beer as that he actually said “teachable moment.” GAAAK!
It’s not entirely rational of me, but Gates lost a LITTLE bit of respect for choosing Red Stripe. I shouldn’t really expect any random person to even KNOW ABOUT the Jamaica boycott, let alone expect them to honor it, but still…
Perhaps this little selection from Half Moon Bay.
Why is there is a Jamaica boycott?
Well, OK, hop in your time machine, go back and dissuade yourself, if you must.
If I had one eye on the polls, I’d happily quaff a Burning River Pale Ale from the Great Lakes Brewing Co. right here in the swing state of Ohio. Good stuff! Great Lakes Brewing Company - Wikipedia
If I was already serving my second term, I could be easily persuaded to have a Dos Equis, Kirin, Moosehead or Heineken.
First I heard of it.
How about a bottle of homebrew? “This is something I having been working on during the evenings. I keep the kit in the closet in the Lincoln bedroom…”
What, don’t they make Schlitz anymore?