Here is what it is about:
Together for the Gospel is a biennial conference for pastors and church leaders, hosted by Mark Dever, Ligon Duncan, Albert Mohler, and C.J. Mahaney. You can learn more by reading their blog, visiting the 2008 conference info page, or watching video highlights from the 2006 conference.
I just found that all of the messages are available for anyone to download for free. Just click here.