Thank you.
This also means that to increase anonimity the original client should include
not only 'send to' and 'amount', but also the 'send from' :- )
The concept is called "coin control" and my understanding is that it is being worked on.
bitcoind has this feature in the sendfrom call. If you want to send from a specific address rather than an account, you can combine it with setaccount.