Activision has announced that the Call of Duty expansion pack 'United Offensive', has shipped to retail outlets. I'd expect this is in the USA only and us brits can expect it in about a week.

Activision Deploys Fresh Soldiers - Call of Duty: United Offensive Ships Out to Retail

Effective Immediately - All Personnel are Instructed to Locate Closest Retailer and Obtain the Expansion Pack to One of the Best Games of 2003.

Read the full press release: http://biz.yahoo.com/prnews/040914/latu067_1.html