I hate to be the one to break this to you, but the Palm Pre is about as open as Apple. They have a website where they claim to distribute the source code to their platform, but it is only what they are legally required to distribute. In fact, even that they fall short on: many of the packages aren't compilable as they are holding back on critical header files.
The libpurple-adapter, in particular, must be licensed under GPL (as libpurple itself is), but Palm has been telling representatives of the open source community that they would have to sign an NDA to get access to the full set of files required to make it work, which only be distributed only under a very restrictive temporary license. As someone who has spent a lot of time fighting similar causes with Apple (I'm the developer behind Cydia) I can say that they would
Seriously: if Palm can't even compete to Apple's standards for openness, then you know something horribly evil is going on over there.