GPU specs - more info....
 

http://il2sturmovik.ubi.com/cliffs-o...ion/index.aspx

This latest NEW site says:-
*SUPPORTED VIDEO CARDS AT TIME OF RELEASE:
ATI® : 4850/4870/5830/5850/5770/5870/6870/6950/6970
NVidia®: 8800/9800/250/260/275/285/460/465/470/480

Laptop models of these cards may work but are not supported. These chipsets are the only ones that will run this game. Additional chipsets may be supported after release. For an uptodate list of supported chipsets, please visit the FAQ for this game on our website: http://support.ubi.com

Does that mean my ATI Mobility 1gb 5650 will NOT work? What exactly does it mean - Chipsets?

Don't know, games not out yet.

not sure but maybe its to something to do with what software support the chipsets have, such as ability to run Open GL 3 or later Shaders for example

It means that the game has been tested with this hardware, so if there is an issue, they will support you finding it.

However, if you use a different card and run into problems, they will not accept responsibility.

What, I won't be able to use my 12 MB Voodoo 2? Curses!

It's been explained when the requirements were first announced. It doesn't list the Ati 4890 either and that's what i'm running, but i believe it will work just fine since the earlier and slower 4850 and 4870 are listed.

They confirmed it themselves back then (i think the same question popped up and Luthier answered it), if you have a newer/better GPU than the ones listed you'll be fine.

I think the game will work with your card. Chipset in this context means just graphics card design, in your case ati mobility 5650.