The reasoning for my guesses: C and D are said to only have interest in the Palm patents. This makes sense for Google, which may have no patents at all in this area, and HTC, which may have not as much as the competition (and with the background of the Apple lawsuit).

A and B are said to be interested in both, technology and patents. Lenovo only recently started to get into this business with android phones. It could make sense for them to switch to WebOS. Samsung does Windows Mobile, Android and recently Bada, a linux based operating system. I think, it makes sense for them to build on the existing huge knowledge in this sector and the already existing apps/customers/developers, as Bada just recently launched and didn't get traction yet. Huawei would make sense too, but they are not as deep into the mobile phone business as the rest, i think.