Most definantly
I wrote up a few little books detailing D&D/D20 races in SW as well as Alternity species. And I use several SW races in my D&D games as well.
Sure, it's a little strange when the SW party fights a gang of Drow Elf Soldiers lead by an Ogre Mage Sith Lord, or the D&D party takes on a Rodian ranger and a Wookiee barbarian. However, the systems only require some minor tweaks to work well with each other as far as races are concerned.
The one thing I haven't tried is tweaking classes to work in either system. Granted, classes like Fighters and Rogues are already in both system essentially, and others like Monks and Barbarians would be quite easy to port over to SW, the real problem lies in the magic and Force using classes. How well do Jedi and Wizards/Clerics/Sorcerers/etc. match up? What could be done to Force users to make them balanced with magic users and psionic characters in a fantasy game and vice versa?
Anyway, for the time being, I'm content with simply porting monsters and races between the sub-systems!
Good gaming,
Kiser