Dear Bruno,

Instawallet has always worked like a shared wallet, nothing has ever changed in this respect.

The fact you used to see coins remain at the deposit address simply means that :
 - there used to be less coin turnover,
 - the cold storage was less used,
 - any combination of the previous reasons.

Some stuff does change though, you used to get your transaction ID back immediately when sending coins, that's not the case anymore, sends are now asynchronously handled by a background worker. That's much more secure in terms of potential race conditions, much more robust in terms of infrastructure, much more maintenable (since now I can simply stop the worker, do some work on bitcoind and switch it back on).

The traffic also increases a lot, to give you an idea, our average weekly turnover is around 10kBTC in, and 10kBTC out, it recently peaked at around 50kBTC/week.

Your wallet has exactly the amount you expect to be available, you can't rely on blockchain.info to tell you how much is available in an account on a shared wallet.

This is how your balance is calculated :



Hope it's clearer