Microsoft (and Apple) did a similar thing back in 1996–7 with "core fonts for the web" in which they tried to push a standard pack of fonts out to everyone so that web designers could assume that end users would have certain key fonts.
http://en.wikipedia.org/wiki/Core_fonts_for_the_Web
It's not some big conspiracy, it's about making the web easier to use, easier to read, and easier to design.
That and making it easier for developers to make better websites encourages more usage of the internet .
TypeKit helped build part of this (http://code.google.com/apis/webfonts/docs/webfont_loader.htm...), so read what you can there.
My thought is that they're hoping this will encourage more text instead of images as text. That helps them index more information and collect more data on the whole web.