1. A
phrase people use because they are apparently unfamiliar with the
English language and do not realize it doesn't make sense in most contexts they use it in. Most of the time, they mean
for all intents and purposes, which does have meaning; that is, that the
reference is practically what the
speaker is talking about. An error much like saying "the team should
of won" when meaning "the team should
have won."
2. Also, very rarely, correct, as in "4 GB of
RAM are good for all intensive
rendering purposes."