Yes, you can do this.... but if you have a thousand contacts, you should wait a little bit.

BlackBerryOS 4.0 lets me have multiple addresses per contact -- a Work address and a Home address. And Categories too, so it works great now.

Should be out sometime by the end of the year for many carriers, and early next year for other carriers. I am using 4.0.0.124 beta now and it seems to be almost production quality now (not publicly available, unfortunately).