For those of you interested with the current development in the works for this firmware, check out the following link:

T2i/550D Magic Lantern Firmware Wiki

T2i/550D Magic Lantern Discussion Group

As per the wiki, the firmware "adds new features like onscreen audio meters and zebra stripes, as well as disables the audio AGC. It is an open (GPL) framework for developing extensions to the official software, tailored for film making needs. It does not replace the existing firmware, but instead runs along side of it. There is no need to "uninstall" it -- simply power cycle the camera to reboot to the stock Canon firmware."

Here's a link to donate to the Magic Lantern team:

My little feature request:

Current: The wheel controls shutter (the one thing I don't want to change), use AV + wheel to change aperture.

New: The wheel controls aperture, use AV + wheel to change shutter.

- Carl
http://slugco.com

HOLY CRAP!!!!!!!
http://magiclantern.wikia.com/wiki/550D

Let us know how that goes, and possibly post a small HOW-TO, please...!!

 This is the info from the Magic Latern Blog:

"Hi,
Please find ML for Rebel T2i/550D ported to firmware 1.0.9.
"magiclantern.fir" file size as been optimized, so that CO2 footprint is
reduced, as well as decryption/signature check time ;-)
I added a configuration variable to disable bootdisk flag, see mlantern.cfg.
Already tested 10-15 times, so risk is very low, but never zero...as usual.
http://bitbucket.org/hudson/magic-lantern/downloads/magiclantern-0.1....
Indy "

Signing in, need AGC update

Okay, happy fun time!  I've got Magic Lantern on my t2i.

Here are the steps I took (I am not responsible if you screw up your camera or anything else following my directions)!

1.  Update the Canon Firmware - Update the Canon firmware of your camera to 1.0.9
      - To find out what firmware version you're on, turn on your camera, set it to 'P', click menu, go to the third Wrench, then click the Firmware button.
      - If you don't have Firmware 1.0.9, download it here, then format an SD card, extract the .fir file (by clicking the .exe file) to the card, put the card in the camera, turn on the camera, go back to the firmware screen via steps above and update the firmware.

2.  Download EOSCard - This utility is required to make your SD card bootable.  It can be downloaded from here.  Download it to any folder on your computer.  Format the SD card you plan to use to run ML off of.  Once formatted, run the application and check the EOS_DEVELOP and BOOTDISK checkboxes.  Then click Save



3.  Download Magic Lantern - The latest Magic Lantern firmware can be found here.  Download the zip file and extract its contents to the root folder in the SD card that you made bootable in Step #2.

4.  Put the card back in your camera, turn it on, and voila!  If at any time your camera hangs, turn the camera and pull the battery out.  The Magic Lantern Firmware will only work when you use the SD card that you moved the ML files to.  If you stick another SD card in there, it'll load back to Canon's regular 1.0.9 firmware.

In my opinion, this is low risk but like I said before, I will not be held responsible if performing the steps above screws up your camera.

Here's another source with installation instructions: Magic Lantern Firmware Wiki - 550D Installation

Here's the online User Guide:  Magic Lantern 550D User Guide

Here's a link to donate to the Magic Lantern team:

Check out Magic Lantern.  It's 3rd party firmware that disables AGC.  I've running for the last week and it's awesome!