The button disappeared and the shortcut changed but it's still here: Ctrl + Shift + e

You can add the button back if you want. Right-click on a toolbar and choose Customize. You can then drag and drop the "Tab Groups" icon from the customize toolbar dialog back onto the toolbar.

Isn't it a bug that ctrl-e now does nothing? (what happened to restoring it to the search shortcut, i.e. equivalent to ctrl-k?)

I'm just wondering why this was changed? How are new users suppose to find this awesome feature if there's not even a button in the interface for it by default...

Due to a number of issues with panorama, it was decided to remove the icon from the default interface. They are trying to avoid cases where people accidentally activate panorama. They need some time to fix the issues but don't want it to delay the release of Firefox 4.

Whatever the developers have in mind, they don't really care much for Windows shortcuts (especially when they're coming from Microsoft). Here's a little something that may help:

https://addons.mozilla.org/en-US/firefox/addon/change-panorama-shortcut/ https://addons.mozilla.org/en-US/firefox/addon/change-search-shortcut/

Have fun! ;)