On the feet of the latest Firefox update, comes a new beta (14) with a handful of important updates, ready for its six week general testing cycle.
The user interface gets flat buttons (back to 2.0 days) for a cleaner interface. Also, web sites favicons are no longer displayed as they may be used to spoof a secure (SSL) connection. This way, now should focus on the highlighted domain name.
As you enter text in the location bar, in addition to suggestions, Firefox autocompletes for faster access to your history and bookmarks.
While not enabled by default, the option to manually activate plugins is already here. To enable it, you need to set plugins.click_to_play to true via about:config. Once done, plugins will be replaced by black images you have to click to play. This is similar to Flashblock, except this works for all plugins and not only Flash.
Note that there are reasons for this feature to be disabled. For example, if you click on a certain plugin in a web page (say, a video) it also enables other plugins (like a pesky Flash ad), limiting its intended benefit.
For web developers, Pointer Lock (necessary for FPS games for example) and a way to prevent the computer from going to sleep (like when watching a web video) APIs are now available, as well as pseudoclass inspection.
If you want to help try these features today (a full 6 week cycle ahead), grab a copy from Firefox Beta site.