According to Profootballtalk.com:
A league source tells us that the New England Patriots already have advised receiver Donte’ Stallworth that they won’t be picking up the $6 million option due to be paid to him on or before February 25.
As a result, the Pats will be required to cut Stallworth by 4:00 p.m. EST on Friday, February 22. Unless, of course, they work out a new deal with him before then.
Stallworth was signed by the Pats before the team acquired Randy Moss. The decision not to keep Stallworth suggests that the team will retain Moss, possibly by applying the franchise tag to him and then trying to work out a long-term deal.
The deadline for applying the franchise tag is February 21.