Why are they required to release those datasheets?
That Broadcom doesn't do this is very atypical.
All this said, if you want cheap and software open, go with the Odroid C1 (China really is the future, and in this case a Korean firm is acting as the intermediary to Chinese silicon.) And if you want fully open, TI's Beaglebone. Good, solid, open, American.
According to http://www.hardkernel.com/main/products/prdt_info.php the Odroid C1 uses a Mali-450 MP2 GPU. This is at least as closed as the VideoCore IV used in the Raspberry Pi.
"We designed our storefront to be indistinguishable from something resembling an sslstrip attack in action" leads to an "I guess I'll have to do without, then" response.