This huge update to the game, one of the largest to date will feature a new spider boss, faction classes, capes, character leveling plus a host of changes to items, areas and game mechanics. I’m pretty sure the free to play month will kick in at the same time.

This is due to be released on Tuesday, August 9th. Here is the release notes:
http://universe.lego.com/en-us/community/newsnetwork/story.aspx?id=343093