My 52.39 btc is also 'missing' sent from one instawallet to another address and the coins are not showing up in the block chain, and the new address isn't showing up either cause its never been used.....

and yet on the address where the 52.39 btc were sent from shows unspent coins but they are no longer in the instawallet

http://blockchain.info/unspent?active=17iQhdkNpoxYcNNcXodPjTWUqSuTC8XaF4&format=html