linux-next in short words is a git tree that is the merge of all of the developer and maintainers trees, much like the -mm tree is today. There are some automated buildtest and maintainers get notification on merge and buildproblems. For a more detailed explanation please have a look at the initial announcement of linux-next.
Currently Stephen Rothwell is taking care of this, but Harvey Harrison, Ann Davis and Frank Seidel are also ready to help and backup Stephen (once we figured this all out).
The short summary will give you a quick overview what and where to find things.
