The latest range of upcoming Microsoft products have given up the conventional "standard" window elements like the menu bar and the toolbar. These are replaced with application specific UI items giving a whole new meaning to menus and toolbars.
Back in our computer studies courses, we were told to make the UIs look consistent, intuitive and "learn-once-and-apply-it-anywhere", and most of the apps today conform to these guidelines. But these theories no longer hold true for the upcoming Microsoft apps.
Have a look at Windows Media Player 11:

Windows Media Player 11
What you have is a border-less UI with a fancy skin you have to figure out. What used to be the blue “Title Bar” of a window is nowhere to be seen, and what looks like a skinned version of it now also shows the song play duration and length!
The 'standard' menus and toolbars are gone. This is replaced with what looks like a tab-pane which has buttons that light up and sub menus of their own when you click the small arrow beneath them.

Windows Media Player 11 with context menu
You still can access the main menu by right-clicking on the title bar, and even turn on the menu you used to have which is now called the “Classic Menu. But once you do, it totally ruins the skinned look.
Now have a look at Windows Live Messenger 8:

Windows Live Messenger 8
No menus and toolbars here either. If you try to access the main menu by right clicking on the title bar, it won’t work here. You got to click the new icon in the title bar (right before the minimize icon) for this. It takes 3 seconds to figure this out, but now you have two Microsoft apps that behave differently and look different.
And now the Microsoft Internet Explorer 7:

Internet Explorer 7
No menu, and umm… the toolbar is not a toolbar but a bunch of buttons scattered all over the place. And how do you get the menu? Right click on the title bar? Won't work. Is there a tiny icon before the minimize button? Not there. Ok, right-click on the empty tab space. Ah, there you have it - the option to enable the 'Classic Menu'.
Now you have three Microsoft apps that behave differently and look different.
Have a look at Windows Defender:
Windows Defender (formally Microsoft Anti-spyware) now runs behind the screens to protect against spyware. It's
free!


Windows Defender
There is simply no main menu in Windows Defender and everything is controlled by the couple of buttons in the tool bar. The "Tools" button is no longer the Tools menu, but a button that changes the UI to show the "tools" available.
How is that? Now you have four Microsoft apps that behave differently and look completely different.
Now the upcoming Microsoft Office 2007:

Word 2007
Great... a whole new UI. What looks like a toolbar/menu bar/tab pane combination, with buttons of all sizes and icons of all sizes, some with text and some without, is the ultimate UI change to follow. This whole new combined UI thing clearly deserves a new name...and the new name given is – Ribbon!
The Ribbon will come in all the Office applications, dynamically changing the buttons and tabs to show what is relevant to do your current task.

Excel 2007 in a black theme

Office 2007 - New mail
What used to be the Tile Bar now has a big office icon on the left, called the "Office Button", which acts something like the old File menu. As you can see, most common buttons like the save and undo are stashed right on the "Title bar" – or what is left of it.

Office Button in Office 2007 applications
To conclude, now you have
at least five Microsoft apps that behave differently and look
completely different.
Where are we heading? When Windows Vista time comes, most Windows applications would be having their own UI implementations and behavior -- and that is going to be the end of consistent UIs. Stay tuned.
PS: Quick Tip: To quickly show the standard menu bar in all of these apps, you can simply hold down the Alt key!