One of the less-heralded features in the forthcoming Office 2010 is a change to how copy and paste works. While the new "Live Preview Paste" is an improvement, it's still a little fiddly and inconsistent, especially for keyboard shortcut junkies.
The Office 2010 Engineering Blog offers a detailed outline of how the new paste option (which is designed to eliminate the all-too-familiar "Paste/No that's not right/Undo" cycle) works. If you use right-click to access paste, you can mouse over live Ribbon-style preview buttons to show the impact of choosing various options, such as keeping the source formatting, merging with the document formatting, or just pasting raw text. What options appear depend on the kind of content you paste.
For keyboard shortcut users (and Control-V must be one of the most used shortcuts around), there's also been tweaks. After pasting, you can hit the Control key (on its own) to pop up a similar dialog of options, and can use "keyboard accelerators" (single letters on their own, as used in the Ribbon) to access them.
While this is a neat idea, I don't think it's been executed very intelligently so far, particularly for keyboard shortcut users. For instance, to paste unformatted text, you can type Control-V, then Control, then T. However, the dialog that pops up doesn't show you what the keyboard accelerators (T in this example) actually are - you have to mouse over to learn what they do, which pretty much defeats any speed gains.
While you can move around the pop-up dialog with the arrow keys, you can't access any previews without using the mouse either. The keyboard accelerators do show up in the Paste button on the Ribbon, but only a sadist would routinely type Alt then H then V to access the Paste feature.
There's also inconsistencies in how the previews appear if you do use the mouse to access them. In Draft mode, they don't appear at all, even when the resultant formatting would actually be visible in the Draft view otherwise.
For my money, it's still simpler to set up your own keyboard shortcut for pasting unformatted text (I use Control-Shift-V). Not only is that faster to type than the new alternative, it also executes much more speedily, especially if you're pasting text from a web page, which is still a painfully slow process in Word 2010. Using the new method, you have to endure that long delay, but a macro-based shortcut skips that entirely.
Live Preview Paste - Get the Results You Want Quickly [Microsoft Office 2010 Engineering]