Yes, the multiplayer ladder is separate.
It's not that complex actually, it's just in its own little title.
You can easily build platform tracks by going to the platform title and opening the editor there. That way it uses the Platform script when you're creating your track, instead of the regular script for playing Race maps.
Platform is all about finishing in the least respawns. It's really that simple.
If played online, it's about finishing with least respawns as quickly as possible so that you can do the maximum amount of runs in the given timelimit, thus getting the best rank on the server for that round on that map.
Getting to play Platform maps online in its own gamemode is an entirely new thing we've never been able to do before.
Bear in mind that the Platform Title Pack was not developed by Nadeo. It was created by a separate studio, Nadeo Live. So while Nadeo continues to put the finishing touches on ShootMania and work towards Valley, Nadeo Live is able to focus on extending the game with the social things... ManiaPlanet Store, ManiaHome, new titles like Platform, etc.
The cool thing is that we can also now make our own title packs.
This isn't really something that new though. In some older TM games, users were able to make their own campaigns and distribute them. And in TMUF there was the "My Campaign" feature that let you set official times on community tracks and gain Skill Points from them for the Solo ladder.
So this is just an evolution of things that came before.