[Acer Iconia A500] dude64:
Leaked 3.1 to official 3.1

Yes it is, just a little confusing though. You have to know which region your tablet is from http://secure3.tx.acer.com/FindSystem/FindSystem.aspx?title=Information About Your System. And then go about flashing a couple of ROMs to get you ready for the update. Instructions here:

http://xdaforums.com/showthread.php?t=1155664

I am a total noob and wasted my whole day yesterday trying to figure this out. In the end texonex helped me out. Starting with the leaked 3.1 update here's what I did (courtesy texonex):

1. Root the device (http://xdaforums.com/showthread.php?t=1138228). Download Acer Recovery Installer from the market, and from there install the clockwork recovery image. Choose no for a backup of the current recovery.

2. Download the backup file for 1.104.02 here, thanks to camelot1972

dl.dropbox.com/u/34113636/2011-06-24.12.20.13.zip, I guess you could also use the file from here: http://xdaforums.com/showthread.php?t=1113878. This is for the US version.

If your tablet is from another region you would have to find the appropriate "default" version number in the how-to (what firmware is right for my country).

3. Extract the contents from the zip file and put them in the backup folder for clockwork mod on your SD card (take your SD card out of the tablet and connect directly for all the steps), if you do not see the backup folder, I suppose you can make one,e.g. [micro sd]\clockworkmod\backup\2011-06-25.22.14.07. I guess this exact string will still show up in clockwork recovery. I made a backup of the leaked 3.1 and that gave me the folder, and I just replaced the files. The date part is obvious in the name however I wouldn't venture a guess what are the other digits in the folder name.

If you downloaded the file from [OTA] Full Package and Update page, you'll need first to decrypt the file using the decrypter and then extract the contents of the decrypted file. One of the extracted files is update.zip which goes on to the SD card no subfolder in this case.

4. Restore the firmware using CMW using full restore for the US version, or update from the sd card zip if using a full package zip file.

At this point I think you need to save the recovery image for the non-US versions. Follow the instructions in the how-to or just use acer recovery installer to flash the clockword recovery again and this time choose yes to backup the current image.

5. Download 1.104.02 to 1.141.07 update and flash it with CMW.

Or the appropriate latest update file from your region(highest version number).

6. Flash recovery image to 1.141.07, this is option 4 in Acer recovery installer.

For non-us versions restore the recovery image, unroot and restore factory defaults.

7. I stopped here and now am waiting for the OTA. According to the how-to, you roll back to the full defualt package by using the standard ACER recovery (Power + -Vol) after copying the zip file on to the SD card, delete the zip file copied before.

8. Go to settings and trigger update manually. OTA will prompt you the new 3.1 update. I suppose you do not need to unroot.

You can also install the stock ROM from here:

http://xdaforums.com/showthread.php?t=1159443

Thanks to Bec07 (how-to), vache (stock roms) and sc2k (un-rooting) for their contributions or I would have been totally lost in trying to downgrade my tablet from the leaked 3.1. Hope this is helpful, and goes smoothly because if it does not I wouldn't have clue how to fix it.