Forefront Threat Management Gateway (TMG) 2010 Feature Pack 1
A first feature pack will be released soon to add some significant features to TMG 2010.
Rule based routing
NAT and Route per firewall rule. So you can break down dedicated traffic to each ISP connection.
Protocol based routing
NAT and Route per protocol definition. You can now define on protocol level which ISP or IP address will be used for outgoing traffic.