The logistics of the update are being discussed in https://groups.google.com/forum/#!topic/mozilla.dev.planning/h_DvC6WnFx0 https://groups.google.com/forum/#!to

The logistics of the update are being discussed in https://groups.google.com/forum/#!topic/mozilla.dev.planning/h_DvC6WnFx0 https://groups.google.com/forum/#!topic/mozilla.dev.planning..., with the current proposal available at https://wiki.mozilla.org/MPL_Upgrade https://wiki.mozilla.org/MPL_Upgrade. One idea is to update the codebase at the beginning of the cycle that will end up being released as Firefox 13.