Minecraft 1.7 is available to play through a first snapshot, published yesterday.
Minecraft 1.7 is mainly focused on “Biomes”. It introduces new biomes: Clay Canyon, Redwood Forest, Stone Beach, Savannah, Roofed Forest, Ice Plains Spikes, Birch Forest, Flower Forest, Deep Ocean…. Biomes have been put also in four categories (Snow, Cold, Medium, Dry/Warm) and they will attempt to avoid getting placed next to a biome that is too different. Now you should not see lot of deserts just after a snow plain.
The changelog is very huge and we invite you to discover all the new features here: http://www.minecraftwiki.net/wiki/Version_history/Development_versions#13w36a
If you are looking for a server to play Minecraft 1.7, you can find 1.7 servers here: http://minecraft-mp.com/version/13w36a/