We will probably never support firstbits addresses, think about it for a minute, by inputting someone's address I can instantly find out whether this person transacted with Instawire, what this person's IBAN and name are. Probably not the best idea when firstbits are often part of forum signatures.
How does requiring the full address lessen this exposure? If the reason you don't support firstbits is because you divulge personal information given a bitcoin address with the assumption that only the correct account holder will be able to provide the entire bitcoin address, how do you reconcile that with the fact that anyone can look up the full address for any firstbits on the internet and query with that instead? In fact, the total set of bitcoin addresses ever used is very finite and publicly available, and someone could just query your server for every bitcoin address that has ever been used since your service started and datamine your entire database.