I have 1000 raw photos that I would like to convert all to jpg. Is there a way I can do this all at once or can I only do it one by one?
In Lightroom, open the catalog with the photos, select the collection or filter so that only the files you are interested in are shown in the library grid (or undo a filter/collection if you want ALL files).
Select all the files by choosing Edit | Select All (CTRL+A on Windows).
Export as JPG by choosing File | Export (CTRL+SHIFT+E on Windows).
In the Export dialog, choose your output folder, whether you want the JPG files added back to your catalog, and the output settings (resolution, sharpening, etc...)
And you're done!
(Note, I have Lightroom V2.7, but I suspect this process is the same in Lightroom V3.x).