basically when you call listaccounts call it will show you accounts as key and balance as value ( it's quite usefull when you have multiple addresses pointed an account(label)
i think getaccountaddress call is what you are looking for .
PS: btc supports rpc2.0 this makes your life easier.
I tried getaccountaddress and found stange results, it sometimes generates a new address with the same label as the argument !! How does that work ?
Also any link as to how and what advantages rpc2.0 has when used with btc ?
about rpc2.0 http://www.jsonrpc.org/specification#examples
I'm sorry for the mistake.