Instead of supporting a particular browser version for just six weeks, an "extended support release" (ESR) would be supported for a total of seven Firefox release cycles, or 42 weeks.
Mozilla would still be updating an ESR version every time a new Firefox is released, but would only apply security patches, according to a proposal. If Mozilla starts this idea with Firefox 8, then ESR versions would be called 8.0 ESR, 8.0.1 ESR, 8,0.2 ESR until 8.0.6 ESR with release dates that coincide with Firefox 9 - 14. Mozilla also said that business that choose the ESR version will have 12 weeks to qualify a new Firefox ESR version once it becomes available. The current proposal suggests that Firefox 8 ESR will be introduced on January 1, 2012 while the will not have to switch to the successor Firefox 13.0.1 ESR (including two qualifying cycles) until August 28, 2012.
Mozilla is currently asking for feedback on the proposal, but said that it is planning on launching the ESR versions with Firefox 8 or 9.