Re: "simply market forces in action"
I'd agree that it's the landlords who are to blame, for upping their rents, but I don't see the "trickle down" argument.
If you're living in rented accomodation, and earning minimum wage from Starbucks, when the rent goes up, you'll be out on your ear. Starbucks might do very well out of selling lattes to the incoming "techie scum", but I doubt that they'll be "trickling down" the profits to you.
Maybe the protesters are picking on the big corps, because the big corps have the resources necessary to behave in a socially responsible fashion? They could picket the landlords, but I doubt they'll give them back their houses.