From Jim Gintonio from the Arizona Central:
Diamondbacks ace Brandon Webb, who will miss at least six more weeks with a strain in his right shoulder, is not concerned that the injury will affect him on a long-term basis.
A much-quicker return was expected until Webb encountered problems Friday. He now will shut down for a week and then begin strengthening his arm. He will not throw for three weeks. He said he cannot recall any one pitch that caused the problem, saying it probably was something that occurred during spring training.
I bolded the "at least" in the opening paragraph. I wouldn't expect a healthy Webb until the end of June.
You obviously can't deal him now, but all you need is one or two good starts from him when he returns to get some value for him come the trade deadline in your roto/fantasy leagues. Should he return to form, Webb could help some teams looking to play for "this" year in keeper leagues.
But one thing you might want to consider is the way Arizona is playing now. If the team falls out of the race early, they may want to hold him back as long as possible to ensure his health for 2010. Webb may prefer that also as 2010 is his walk year.