I am happy to report that we have now got word that Motorola Atrix users that are rooted can now get HSUPA speeds on their device, but not from AT&T, not yet. This comes from XDA forum members drew.man and NFHimself. They have fixed this issue that we have all been reported and waiting on, and were nice enough to share it with the rest of you Atrix owners.
I will mention that this is a slightly involved process, and as always make sure you are careful, and do anything like this at your own risk. I like to have anything and everything backed up before tackling anything like this. In order to do this, you will need a rooted Motorola Atrix, the modified SBF files, and RSD Lite, the program used to flash the SBF files to your Motorola Atrix.
You can do the fix provided by these awesome developers from XDA, or just wait it out for whenever AT&T decided to roll out the "fix" we have heard them mention more than a few times. This is a simple radio flash, but as always use caution. You can read more over at the thread on XDA, or check out the source for full instructions.