Bert and Ernie were best friends in the movie "It's a Wonderful Life." Jim Henson later named two of his popular muppets Bert and Ernie after those characters.
It sounds ugly and old-fashioned to me. If you really like the sound, I suggest you name your son Burton and call him Burt, preferably with that spelling. It just looks better. As for the use of this name in other languages, well, it can't be short for Burton, so you shouldn't use it. It's just awful.
Famous fictional bearer is Bert from the Mary Poppins books, movie, and musical, Mary's friend and a jack-of-all-trades.
-- Anonymous User 12/7/2009
I hate this name. Any name with "Bert" in it makes me picture a heavyset guy over 40 with a big round red nose. It's so silly, there's no flow, no elegance, "urt" is not a nice noise and sticking a "b" on it makes it worse, and it sounds like a neologism for passing gas from both ends at once.