The only way to use an image outside LR is to Export it.
The changes you make to your image are in a database file and are only applied upon export.
LR does not change your original image.
So a simple Copy/Paste into another program is not possible.
Well that stinks!!! I understand about about the mods and how the image is stored, etc. But if LR can render to the screen and to external files it *should* have the capability to render to the clipboard (something along the lines of, right-click, copy to clipboard. My work-around to get an image into MS Word is to use an image viewer and take a screencap of the image in lightroom.
For every 2 (or is it 3?) things Adobe does right they do 1 thing wrong - never fails.
In my opinion, it is better to insert properly saved and compressed images "from file" into Word, rather than pasting them ad-hoc "from clipboard". The more formal method takes control over the image compression and format, and thus keeps a lid on the potential image bloat of the document. With copy-paste anything may happen; and often does.
So if you are inserting (or linking) a file, Lightroom is efficient at making the exact type of file that will be most suitable.
I typically do the screencap using Irfanview - crop and adjust the size and compression type as appropriate then copy to word. I've certainly exported and imported also, and that can have it's merits, but then I end up with filesystem litter to have to clean up, and I try to keep things as low maintenance as possible.
But quality is a real point here.
So you should request a slightly different feature: drag an image thumbnail from LR to Word, which in the background executes the commands
1. Render file as somewhere specified (e.g. In a dedicated export preset for application transfer).
2. Insert the resulting file into Word
3. Ditch the file use for transmission.
4. Update history of the file with this export. - maybe yiu would not be interested in this last point, but it would fit LR logic.
The correct place to request features and let oters vote on them is another forum
If all you want is a quick low-res image, then a screen scrape is going to be fine. If you want to copy anything other than that via the clipboard then what colour space? Resolution? Sharpening? Format (jpeg, tiff etc)? Quality?
I guess they could add something to LR so that when you want to copy to the clipboard, it brings up the export dialog so you can make those choices.
Why don't you suggest it at http://forums.adobe.com/community/lightroom/lightroom_feature_requests
Europe, Middle East and Africa