If you cannot get it yet via searching from an update via your handset (settings -- about phone -- system updates) then read the following guide:
You have to register to download the files. You can also try Streaksmart. At http://www.streaksmart.com/2010/11/h...ll-streak.html
is a special section on upgrading. XDA-developers also has a special section on the Streak.
I have just installed the official 2.2 this morning, after running an unofficial version for about 2 weeks. Yes, the Streak on 2.2 puts Steve Jobs to shame again. Watching the German ARD news Flash video every day, runs great.
But, if you want to root it, Androot doesn't work. The free app Z4root does.