By all accounts I have read and others have expressed, OSCON Java 2011 was a tremendous success. OSCON Java 2011 was O'Reilly's Java-specific conference held in conjunction with OSCON 2011 and the post Why OSCON Java? explains some of the reasons for the Java-specific conference being held last year. In 2012, it appears that the separate Data and Java conferences of 2011 are being brought back into the main OSCON 2012 conference. The page states, "Those who attended last year's OSCON Data and OSCON Java told us that they wanted to be part of the 'main' OSCON, so we're bringing Data and Java back into fold in 2012."
The About OSCON page explains OSCON: "Now in its 14th year, OSCON is the best place on the planet to prepare for what comes next ... OSCON is a unique gathering of all things open source." One example of praise for the OSCON conference is available in the post Why I Won’t Be At OSCON This Year.
According to the main OSCON 2012 page, "roughly 400 people will be presenting" and speaker proposals are due 12 January 2012. OSCON 2012 is to be held July 16-20, 2012, in Portland, Oregon, with registration opening in March.