My boss just bought 2 Dell DLP Projector model 3400MP, and I just finish testing it, it does its keystone by it self !!!
How does it work ?
Can it be a doable mode for our projector ?

If I send the image upper on the wall, the image looks like a trapeze for a second, then the projector ajust it self and look perfect after !

Pretty neat !

How does it work?

Just a guesse, so it may be wrong, but the projector probably measures its own angle of tilt. then it adjusts the picture. Keystone is caused simply by tilting the projector.

Can it be a doable mod for DIY?

Already is. Just let your front fresnel hang freely. If the projecotr tilts up or down the front fresnel will always stay vertical with respect to the ground. The image will be square.

You still run into the limitations of using such a large lcd. The outer corners will become less focused as the keystone becomes greater, so you're still limited to about 15 degree keystone for good unifrom focus - if you are using the 15" lcd. If you are using a smaller LCD then you can probably get away with a larger keystone and stay in focus.

Waow .. I never though of it that way !
That would be a great idea to just let the bottom of my fresnel free so that the keystone will be ok !!
I have to tilt the projector for like... 3 degree