[Acer Iconia Tab A100] FloatingFatMan:
Yes, finally, for us A101 owners out there, a rooting method has finally been found!

Firstly, it's important to point out that I DID NOT DISCOVER this rooting method. All credit for that goes to ZeroNull and can be found in his original post here. All I have done is to essentially translate it to more native English and hopefully explain it a little better. I've been a bit more long winded than ZeroNull was, but it's kinda necessary to make things clear.

Finally, and most importantly:

DO THIS AT YOUR OWN RISK! NEITHER I NOR ZERONULL ARE TO BLAME IF YOU MESS UP YOUR TAB!

You will need a few things:

1. The A10x_Rooting.zip file attached at the bottom of this thread. This contains ADB and SU.

2. An A100 ROM. It's probably best to go for as early a verion as you can but any should probably work. Get one from vache's thread here.

3. An A101 ROM. Any version will do, again you can get one from vache's thread above. Note there are some updated ROMs on about page 13 or so of that thread.

4. The ability to follow instructions CAREFULLY. Seriously, I can't stress this enough. One typo can make the process fail, so copy/paste the commands, OK? :p

5. Basic knowledge of how to open a cmd shell in Windows (I'm not a Linux person, but most of this guide will probably apply).

Right, on to the instructions!

Part One

1. Download all needed file as above and extract into a directory somewhere.

2. Connect your A101 to USB, make sure USB debugging is turned on, and open a command window in the same folder you extracted A10x_Rooting.zip in to.

3. Copy the A100's update.zip to the root of your external SD card on the tablet.

4. Reboot into recovery (hold power and left side of the vol rocker until you see the text).

5. Wait for the A100 ROM to install. This is the slightly scary bit as you just emasculated your tab! :O

Part Two

6. Once your tab has booted, make sure USB debugging is on and go to your command window. Type:

adb devices

If all is well, you'll get your UID in response. You don't need this for rooting, but it's a damn good idea to write this down somewhere safe.

7. Assuming 6 was OK, then proceed. If it wasn't, you'll need to sort that out yourselves

Enter the following commands.

adb shell
/system/bin/cmdclient ec_micswitch '`echo 'ro.kernel.qemu=1' > /data/local.prop`'

Nothing will echo back to you, and trying to ls that folder will give you a permission denied. Don't worry, it should have worked.

8. Type exit at the $ prompt to exit ADB shell.

9. Copy the A101 update.zip to the root of the external SD card, reboot to recovery and flash it.

Part Three

10. Once booted back up, go back to your command window and enter the following:

adb remount
adb push su /system/xbin/
adb shell "chmod 06755 /system/xbin/su"

11. Now you need to undo the qemu command. Enter the following in the command window.

adb shell "echo '#' >/data/local.prop"

Your root should now be 95% complete, but we're not quite finished yet.

12. Load the market and download BusyBox, SuperUser, and if you want it, Titanium Backup. Install all of these but DO NOT RUN THEM YET.

13. Reboot the device. Another scary part!

14. Once booted, run SuperUser then drop back to the desktop.

15. Run BusyBox and go through the install steps. During this SU should ask permission to give BB root access, if it does, it worked! :D

By the way, for me at least, SU moaned about being out of date whilst installing BB. Let BB install, then afterward, let SU update itself.

Important Note

After doing this once, if you install a newer ROM, you will NOT need to go back to the A100 to re-root, that part only has to be done one time. The local.prop file will now persist between ROM's so all you'll need to do is to go back to step 7 and proceed from there.