the esxi 4.1 will support static link aggregation only, with esx 5.1 it support dynamic also.
if you have just connected 2 switches and make it work as redundancy then you may need to break the etherchannel for active/active, else if you have any stacking between switches that is if you have Cross-Stack EtherChannels, MultiChassis EtherChannels (MEC) or nulti switch etherchannel, then you can add 2 pnics to 2 switch and make a ether channel and use the both nics in active active.