As preed promised on his blog, users running the Bon Echo 20060921
nightly build will be offered the chance to upgrade to a "new version"
of Bon Echo in a test of the new "major update" feature of Software
Update. The new version will be advertised as "Bon Echo 2.0mt2", and is
simply a respin of the 20060921 build. Users who upgrade to this "new
version" will continue to get nightly updates as usual.
More information is available here:
http://developer.mozilla.org/devnews/index.php/2006/09/21/todays-bon-echo-nightly-build-update-is-majorly-cool/
(crossposted to mozilla.dev.planning and mozilla.dev.apps.firefox,
please followup to mozilla.dev.apps.firefox)