For Shimano components, the rear shifter will work fine with a mtb rear derailleur; all index-compatible Shimano rear derailleurs except pre-nine speed Dura Ace have the same cable pull ratio, whether "road" or "mountain." Front shifters (indexed) and front derailleurs are "road" and "mountain" specific; "road" and "mountain" use different cable pull ratios.
P.S. One solution would be to use Shimano indexed bar end shifters on your drop style handlebars. They're indexed for rear shifting, and friction for the front, so it won't matter about the front shifter/front derailleur compatibility. Depending on the cable stop arrangement on your frame, you might have to get a bit imaginative with the cable routing-
Last edited by well biked; 10-28-07 at 02:12 PM.