We saw this recently at our most excellent local cinema and can heartily recommended it for a completely easy going, funny and delightful film.
Starring Ben Stiller and a whole host of famous cameos it's essentially about the museum exhibits coming to life at night with often quite hilarious results.
Best performance (out of several) had to be Ricky Gervais. Outstanding.
Take the kids if you need to make an excuse but just go and have a laugh.