To be honest, I'm not all that surprised. Don't get me wrong, I'm incredibly excited, but with the speed and size of the fan response Ubisoft would have been suicidal not to publish it on the PC.
There's a theory that they originally intended to port it to the PC from the beginning, but held back because they knew that fans would try to drive up support, which is equivalent to free publicity. Normally I'd be a little skeptical but considering the increasing prevalence of PC gaming, the possibility that they overlooked the computer as a console actually seems less likely than a marketing scheme.