Maniaplanet Universal Demo is now available at http://maniaplanet.com/

Free access to TrackMania² Stadium, Canyon, Valley, ShootMania Storm and all community-created content. Unlimited play for 48h after registration. Limits apply after that.

The blog post at blog.maniaplanet.com explains, but below are the key details that you need to know...

TrackMania
o 45 white solo tracks
o Access to the TrackMania² multi-environment title (Canyon + Valley + Stadium at the same time!)
o Full multiplayer experience (Nadeo and user-created gamemodes and Title Packs)
o Access to all editors (Map, MediaTracker (Video), Actions & Weapons, Items)
o Up to 3 user made solo & multiplayer experiences

Shootmania
o 3 multiplayer ranked modes: Battle, Elite & Siege
o Full multiplayer experience (Nadeo and user-created gamemodes and Title Packs)
o Access to all editors (Map, MediaTracker (Video), Actions & Weapons, Items)
o Custom Titles: solo & multiplayer innovative modes

All these features are available for free the first 48h for the environments you don’t own and then for an unlimited amount of time for titles with less than 100 concurrent players OR one hour per day otherwise.

Download the setup on http://maniaplanet.com/