yes
I think you mean Pay As You Go and the answer is yes, but it's not unlimited data. AT&T offers 1 MB for $5 and 100 MB for $20. You order it either through 611 or online and it lasts for 30 days. The good thing is that if you refill before the 30 days are up, you can carry over any unused data.
It only works if you don't use alot of data as 100MB isn't a whole lot. if you just check email and do some occasional surfing then it's fine. Once your data is used up you'll get charged lots! $.01/kb which is $10/MB.