The only thing people agree on seems to be that different from is correct. As Kooyeen said, different than is common in the USA. Different to is used in Britain. This is what the Random House Unabridged Dictionary says about different:

—Usage. Although it is frequently claimed that DIFFERENT should be followed only by FROM, not by THAN, in actual usage both words occur and have for at least 300 years. FROM is more common today in introducing a phrase, but THAN is also used: New York speech is different from (or than) that of Chicago. THAN is used to introduce a clause: The stream followed a different course than the map showed. In sentences of this type, FROM is sometimes used instead of THAN; when it is, more words are necessary: a different course from the one the map showed. Regardless of the sentence construction, both FROM and THAN are standard after DIFFERENT in all varieties of spoken and written American English. In British English TO frequently follows DIFFERENT: The early illustrations are very different to the later ones.

Collins Concise Dictionary also mentions different to but says that some people object to it.

CB