Rendering has been updated to 1.6 today! Yay!! 
The update was very smooth although realistically we've been rendreing 1.6 worlds for quite some time after providing support for the new blocks in the snapshots as they came out. I had a blast drawing the hoppers with Python!
If you are using a texture pack:
The new default render system is using 1.6 which also includes support for the new Resource Pack system. If you had previously uploaded a texture pack you will need to replace it with a resource pack to render a 1.6 world properly.
The Vanilla 1.5 and Snapshot 13w19a render systems still use texture packs.
Let me know if you have any trouble getting your resource or texture pack working.
The update was very smooth although realistically we've been rendreing 1.6 worlds for quite some time after providing support for the new blocks in the snapshots as they came out. I had a blast drawing the hoppers with Python!
If you are using a texture pack:
The new default render system is using 1.6 which also includes support for the new Resource Pack system. If you had previously uploaded a texture pack you will need to replace it with a resource pack to render a 1.6 world properly.
The Vanilla 1.5 and Snapshot 13w19a render systems still use texture packs.
Let me know if you have any trouble getting your resource or texture pack working.