Yikes. So far, the only source is the sometimes-dodgy @HawkeyeInsider, and we haven't seen any confirmation of either rumor from other media sources yet. Still, HI might have a less-than-perfect track record with rumors, but it's far less likely that Tarp shows up to practice tomorrow and says "my hand's perfect, you guys!"
At any rate--assuming the reports are accurate--there's no timetable for Tarpinian's return yet. We are working off just one tweet, after all. For some perspective, though, Bills tailback (and Coe College product) Fred Jackson is out for 4-6 weeks with his own broken hand. We don't expect Tarpinian to be gone that long, however, as having two fully healthy hands isn't nearly the necessity for linebackers as it is for ball-carriers. As long as he is gone, look for Bruce Davis or Troy Johnson to get his snaps in practice.
As for Robinson, we'll assume he'll be fine well before the season opener until informed otherwise. Ha, ha, Angry Iowa Running Back Hating God! You missed on this one! You're a bum! Taunting you will have no serious repercussions!
Oh man, that was fun... hey wait, why do I have a Shonn Greene shirsey on? I didn't put thi-- /gets hit by 15 meteors in a row