You may be able to get a minimum of a 1-year contract agreement...but they won't make an effort to sell you this type of contract.
Generally, a 2-year agreement is the way to go (because you may get added benefits).
Only time will tell if AT&T gets a month to month "not contract-but contract" price plan like Verizon Wireless. Verizon Wireless a while back started offering month to month plans where you get all the features and stuff as contract but you weren't contracted. You just wouldn't get any upgrade benefits, etc. A credit check was still required. AT&T doesn't have this type of plan...yet.