I'm pretty sure != isn't part of the ansii standard so may not be supported in all flavours of sql (I actually had to go and try it out in SQL Server to see if it works... it does).

It's also worth mentioning that <> does not mean "Not Equal To", it means "Is Greater Than Or Less Than". It's pedantic but those two meanings are subtly different and can kick you in the pants in some rare edge cases. I've therefore always preferred to use the NOT keyword along with an equals, ie "Where Not 1=0"