Make describe_addresses more efficient when requesting Elastic IP addresses for multiple nodes. It's still pretty bad for the worse case (user has a lot of unassociated Elastic IP addresses), but it's a lot better for the average case (multiple numbers of nodes with not a lot of unassociated addresses).
incubator/libcloud/trunk/libcloud/drivers/ec2.py
incubator/libcloud/trunk/test/test_ec2.py