The 98.19MB file updates the Streak to build 8105, which means the previous version we thought was official (build 8023) actually wasn't. The leaked update, if you're keeping track, was numbered 6941.
What's nice about build 8105, aside from putting our Streaks back onto the path of righteousness, is that it can be applied right over the leaked version. The update notification that appears on O2 Streaks running 1.6 (build 4399) will not show up for the unofficial 2.1 Streaks, but the .pkg can be downloaded manually and installed with no hackery. After the download is complete, just tap on it and the installation will proceed as though it's being applied over an official 1.6 build.
It sounds confusing, I know, but it's really very simple: if you currently have an O2 ROM on your Dell Streak (O2, AT&T, unlocked, beta, whatever), you can apply this update.
I successfully installed it on my O2 Streak that was running the original 1.6 firmware and my official AT&T Streak that was running the leaked O2 2.1 firmware. And other than the download method (automatic for O2, manual for AT&T), the process was exactly the same.
Installing the official O2 update will wipe your device, so be sure to back up anything important before you apply it.
Two additional tidbits worth noting: