New in Firefox 16 * Initial web app support (Windows/Mac/Linux) * Acholi and Kazakh localizations added * Improvements around JavaScript responsiveness through incremental garbage collection * New Developer Toolbar with buttons for quick access to tools, error count for the Web Console, and a new command line for quick keyboard access * CSS3 Animations, Transitions, Transforms and Gradients unprefixed in Firefox 16 * Recently opened files list in Scratchpad implemented * Debugger breakpoints do not catch on page reload (783393) * No longer supporting MD5 as a hash algorithm in digital signatures (650355) * Opus support by default (772341) * Reverse animation direction has been implemented (655920) * Per tab reporting in about:memory (687724) * User Agent strings for pre-release Firefox versions now show only major version and much, much more (full list at https://www.mozilla.org/en-US/firefox/16.0.1/releasenotes/buglist.html)
Not obvious due to summary, but this is a dupe of bug 437780.
*** This bug has been marked as a duplicate of bug 437780 ***