All PS3 users will get Aground and Erosion for free June 15th.
PS3 Elite premium players will get the rest of the June DLC package June 14th.
Content Collection 2 will go up for sale to anyone June 21st, $15.
Here's my summary of the content. But there are already a zillion videos on youtube showing everything, and those are better than a few pictures on a blog.
Here's the MW3 DLC calendar with the same info.
The content collections have been coming out one week after Elite premium members have gotten it, so I expect collection 2 for PS3 to be for sale June 21st.