Ha, I came to post the same thing.
This is what ive done so far.
Tried following this guide
Step 1: Jailbreak iOS 4.3 GM running on your iPhone 4, you can follow the guide posted here using PwnageTool 4.2.
Step 2: Once you’re jailbroken, launch Cydia and install OpenSSH.
Step 3: Now you’re going to SSH into your device (by using clients such as Cyberduck for Mac or WinSCP for Windows), and then navigate to the following directory: System>Library>CoreServices>SpringBoard.app>N90.plist
Step 4: Using a plist editor such as TextWrangler, edit the N90.plist file.
Step 5: Add a Boolean statement “multitasking-gestures” and set its value to “True”.
Step 6: Save everything you’ve edited, restart the Springboard.
Step 7: That’s it, you’re all done! You should now see the Multitouch Gestures option in the Settings.app file on your iPhone 4. Just tap to turn it on.
anyway, I couldnt find N90.plist, but i did find N90AP.plist
Downloaded that file to my mac. Double clicked it and it opened in Property List Editor.
From there opened the pull down menu and clicked multitasking. A plus sign came up on the right side so I added a new item. Called it multitasking-gestures. Made it Boolean. Clicked the box to enable.
Resprung. Mobile substrate crashed. Rebooted, booted up fine. Opened up settings... nothing new there. ( also as a sidenote dont see mobile hot spot in my settings either?)
So, went into ifile, browsed to the same place, and it still says its there and on....
Any suggestions? or anyone get this working?
(For me this is one of the reasons I was excited about 4.3)