I'm not. Google likes to sponsor open-source software, IBM is interested in helping the development of what they see as reliable software (and most likely Gnome is a highly compatible interface with the version of Linux/Unix most of their servers run, or is what they recommend as a shell for the OS they offer with the servers they sell) and Intel, IIRC, wants to support Linux gaming (and since Ubuntu has gone corporate with Canonical, Gnome is a good project to back because of it's simplicity of use). It makes sense, from a business point of view, for these three companies to support Gnome.
Yeah, also the people in charge at IBM seem to have a lot of interest in just making the world a better place. Maybe I'm just brainwashed by their propaganda, but with their lack of consumer products and advertizing, I find it hard to believe they do things like this solely for their own gane.
The GNOME Foundation is a 501(c)(3), IBM's accountants want to make so much in donations a year because tax magic, and they're a big linux shop so they might as well make some of those donations to organizations that directly benefit them. They might not sell linux desktops to computers, but you can bet they deploy them to their developers. If your project has corporate users and nonprofit status you're going to be taken care of.