It's inconceivable to me that after the Linode compromise they chose one of the cheapest shared hosting options with Rackspace and that they didn't regard redundancy and being able to shut down access to the server if it was compromised as critical. They made these choices after they'd performed a security audit which should have revealed that their servers were still vulnerable.
Just to make sure everyone has it straight - Bitcoinica was on the RS cloud long before the Consultancy came along. The Linode VPS was just an attempt to keep the hot wallet off the rackspace cluster to spread the risk around. Obviously we saw how that failed.