The "accounts" feature (to replace "labels") is done for now: listtransactions and gettransaction are implemented, and move, sendfrom, and getbalance <account> are enabled.
This should make implementing web services much easier; you can assign each customer their own 'account' and rely on bitcoin to keep track of exactly how many bitcoins they have, have it return a list of the customer's last N transactions, etc.
This is a minimal implementation on purpose-- for example, gettransaction doesn't return every possible bit of information you might want to know about a transaction, and will only return information for transactions in your own wallet. We are trying to think ahead and not add features that will be broken or taken away when bitcoin supports running in a 'lightweight client' mode, without access to the entire bitcoin transaction history.
I've updated the API wiki page with the new methods.