Backwards-incompatible filter changes in the latest 2011 EC2 APIs
In the latest 2011 EC2 APIs all security groups are assigned a unique identifier (sg-*). As a consequence, some existing filters which used to take the group name now require the group id instead:
group-id filter in DescribeInstances (ie get_all_instances())
To filter by group name you must instead use the group-name filter
launch.group-id filter in DescribeSpotInstanceRequests (ie get_all_spot_instance_requests())
Unfortunately for now, it is not possible to filter spot instance requests by group name; the security group id must be used instead.
This new security group id can be found in the id attribute of a boto SecurityGroup instance.