FBConnect only works with text and texarea fields because that is what is returned from Facebook. For a select field to work, the user would have had to type in the exact information that you happen to have given as options for a select field.
For example, if you have a select field for Favorite Movie, and the options were:
Casablanca
Shark in Venice
Armageddon
But the user in Facebook choose "Airbud", what would be the correct course of action in that scenerio? It would break JomSocial field searching capabilities and cause other issues.
If you have a recommended solution, we'd love to hear it. It's a request we get a lot, but we do call out that only certain fields are importable in the description.