gehrlekrona - 2:18 pm on Sep 22, 2012 (gmt 0)
I too have a lot of mobile users and have had for a while. I created an app for my site that people have downloaded and I have tracked the usage. I agree with @backdraft7 that Google do rearrange the results (see my post above) in that they have lots of different sets of results for the same queries.
One thing I just saw was when I was searching for something for my cat and when the result came up it was kinf of what I was looking for BUT it had a suggestion for me "did you mean...." so I clicked on that and it had a LOT of ads for just a little change of a word/keyword... So yes, the rearrange results depending on how many high(?) paying ads they have. No doubt about it.