EDIT 2/13/2011: for some strange reason this is one of the most visited pages on my blog with something like 100 hits a day. People should not be using this hint anymore. It is very much outdated as Lightroom has a print-to-jpeg function in Lightroom since v2 that works much better than this hack that was necessary in v1.
I was inspired by some posts on the Lightroom feature request forum to make a nice Automator workflow to automatically generate jpegs in srgb (or any other desired) space from Lightroom. Lightroom's printing panel is very nice but I do not own a >$1000 printer to actually take advantage of it. So, if you could print to something like a jpeg and then send it to a development service that would be great. There were a few examples already noted there but none actually did the essential step of converting to another profile as otherwise you end up with an image in Generic RGB, which will print way to dark from most printing services. So here is a workflow that does that. If you do not see the entire screenshot, make your window wider. There is a larger copy in this link.
To recreate this, first drag a render pdf as images action into the right part, select color model RGB, format jpg and a high resolution and high quality. Then drag the Apply colorsync profile to images below it, select an sRGB (or any profile you desire, such as maybe a profile supplied by the printing service) profile (there are typically several, it doesn't matter which one you choose). Lastly, drag the New folder action below and set it up as you want. The service will create this folder if it doesn't exist or simply throw the files in the folder if it already exists. Now save the workflow as a plugin for "Print Workflow."
Now, whenever you print, you can simply select this workflow as in the screenshot below
And you'll end up with nice jpg files directly from the Lightroom print module in a usable color space! You can add borders, put multiple images on the page and add your logo!
UPDATE 9/7/07: Apparently, this action might fail if you have enabled FileVault on your machine. If you have that make sure that the folder you export to is outside of your home folder.
UPDATE II: More info here.
UPDATE III: A method to add logos and such to exported images