I'm sure the Dell Streak 7 will have an array of official accessories when it's released but for now, this OtterBox Commuter Series case I found stacked on a bottom shelf in Dell's CES suite will do just fine. This was the only accessory I saw for the device and the only reason I realized what it was is that I thought it was a new case for the Streak 5 (I guess we have to start calling it that now). It was sitting with all the other Streak 5 accessories (nothing new there), and I only picked it up because I didn't recognize it.
Typical of all of OtterBox's Commuter Series cases, this one features a silicone inner lining and a hard plastic outer shell. It also has a silicone plug for the PDMI connector at the bottom and raised coverings for the power and camera buttons at the top.
Interestingly, it's also got the Dell logo on the back. There was a "not for resale" sticker on it too, though, so maybe this isn't the final version.