The Dell Streak 7 was released to the masses just last month and it's already got its first official OTA update from T-Mobile.
The update takes the Tegra 2-powered tablet from Android 2.2 (build 14291) to Android 2.2.2 (build 15420) and includes a new power management profile, Qik enhancements (hardware acceleration and improved video quality), improved camera performance and MMS, updates to some preloaded apps, and "general performance improvements." It also boosts Quadrant benchmark scores to 1900+!
An automatic notification should appear to alert you to the update, but if not, you can check for it manually by going to Settings > About > System updates.
If you've flashed ClockworkMod Recovery, the package won't install and you'll likely get stuck in somewhere undesirable like the Dell logo or that screen with the Android mascot being dwarfed by the triangle with the exclamation point in it. To get around this, you'll need to flash back to stock.
[Update: All the files you need can be found in this post by bogdi1988. Once everything is on your Streak's internal memory (not the external SD card), follow these instructions by bogdi1988. Yes, bogdi1988 is a Streak savior!]
Oh, and is typical with OTAs, this update will cause you to lose root. There are currently no known methods to get it back again, but I think a solution should be coming out soon.