Although there is an official mobile version of IMDB it doesn't seem to be working and hasn't been working since I first tried it a couple of weeks ago.
There is, however, an alternative: Mdog's interface to IMDB
It's very functional and is perfect if you want to check some basic facts while watching TV or a DVD (more likely a DVD in my case). Admittedly some of the functions of the "normal" site don't work, but I can live without them. In any case it's better than having to boot up my laptop just to check some movie trivia
UPDATE August 2011
Checking my stats this post is obviously still quite popular
IMDB have now got a mobile version of the site and also have apps for popular handheld devices such as the iPhone and iPad.