Well, I for one am using Wasia firmware and quite happy with it
Version number on the menu still shows 1.1.1, but I now have a custom function menu with 17 customizable functions available 'à la 10D'.
The firmware itself it is quite easy to find, just look on google for 'Digital Rebel Tips and Tricks' and click on the first link that comes up... great info on that site as well.
Contrary to popular belief, it won't hurt your camera if you do the upgrade...the original firmware is still available from Canon, and you can always revert back to it if you ever need to...
Aviation-wise, you won't get much improvements from instaling it... you can use the SET button to change quality, prevent the shutter from firing when there's no CF card on the camera, and you can change the focus from One shot to AI
For portraits it is invaluable... you get 1/200 flash sync speed, ISO 3200 for really gritty pictures, and the much needed Flash Exposure Control (FEC - for controlling the intensity of the flash between -2 and +2 stops).
All in all, it is a great upgrade for the camera. I've installed it in July, I think, and have never looked back since