I have lived near a few that where quite authentic, Finnegans Wake in Key West was THE best hands down, AMAZING food, TONS of import ale and dark beers. And 3 "import" Irish Lasses waiting tables, that accent gets me goin every time
http://keywestirish.com
Calaghans in Mobile Al.
http://www.callaghansirishsocialclub.com is close, and was the site of Shannon and mines wedding reception

McSherry's Irish Pub in Fairhope Al. is even owned and operated by a couple Irish Ex-pats Ronin & Barb McSherry These three are great. THeres also one in Pensacola FLorida Mcguires
http://www.mcguiresirishpub.com which has its own BREWERY in-house!!!!!!!!.
I guess even a chain like Beef O BRady's would work in a pinch however they really aren't much of an Irish Pub other than in "name" alone.
As you can see I have done a bit of research in this area. Nothing like a good, cigar smoke, old wood and stale beer smelling dark Irish Pub. Unless its one with a big screen T.V. playing the Isle of Mann race or a good rugby match....oh......Heaven.
I'll bet a few of our European contingent can get a pic of a REAL Irish Pub for sure. Lets see 'em, Hell even if you ain't the first, post em up anyway!
Pics of Bangers and mash, Shepards Pie or a good Reuben sandwich lamb stew or fish and chips get ya extra points. Crap now I am hungry ...."SHANNON!!!! Do we have any corned beef?!?!?!?!?!"
Gotta go!