Well this is something that people have been demanding for quite some time. Not only will Capcom's Street Fighter V be available on the PC and PS4, but multiplayer can be a mix-and-match between the two platforms. You will not need to coordinate a platform of choice ahead of time. Players on both of these platforms will be able to connect to one another.
While Capcom has not released any further details, previous Street Fighter releases for the PC have supported local multiplayer when extra controllers are connected. The omission of Xbox One is definitely strange as well, given the exclusive agreement between Microsoft and Capcom for Dead Rising 3. Of course, different game, different contract, but it suggests a larger reason to avoid Xbox One. Two possible, not mutually exclusive reasons are: 1 – Sony paid them and/or 2 – Microsoft was too restrictive about cross platform play. In the past, Microsoft would only allow PC-Xbox cross-platform play if the PC title was branded as Games for Windows Live, which I do not think any game took advantage of (Update: Apparently I was wrong and Shadowrun actually launched cross-platform multiplayer before it was sunset). It also no longer exists.
Street Fighter V will be out… sometime… for PC and PS4.