BGP peer groups no longer a performance feature
In Cisco IOS release 12.3T (integrated in 12.4), we've got an interesting (and quite understated) BGP feature: BGP peer-groups are no longer a performance feature (previously, IOS used them to reduce the time needed to compute outbound BGP updates). IOS now performs automatic grouping of BGP neighbors in dynamic update peer-groups that receive identical BGP updates based on per-neighbor outbound parameters.