I have the the get started tab installed, but I prefer to use the downloaded version of the 2003 to 2007 command mapping flash applet to the online one.

http://office.microsoft.com/en-us/training/HA102295841033.aspx - this page has links to online and download versions of the flash apps that show mapping of Office 2003 menus to 2007 ribbon. It also has links to the (really big) spreadsheets that have all of the 2003 commands mapped to 2007

2.1 Search Command Addon
http://www.officelabs.com/projects/searchcommands/Pages/default.aspx - SEARCH Commands, Office 2007 addin. Type a command into it, it displays all of the possible command matches.

http://blogs.techrepublic.com.com/msoffice/?p=139 - 10 new Office 2007 interface elements. This blog describes all of the new Ribbon UI elements very well. Actually, I've managed to push it up to 16 elements.

- http://technet.microsoft.com/en-us/library/cc179199.aspx - The "official" MS "Changes in Office Word 2007" pages. Is part of a site that has "changes in ..." all of the Office 2007 applications. Great spot to get all of the details, "from the horse's ..."