Our current Exchange servers have 2 Intel PRO 1000's in a Switch Fault Tolerance mode. There are no IP's assigned to the individual NIC's. There is a single IP assigned to the team. No problems.
Some in my group are proposing assigning IP's to each NIC and the virtual NIC for our upcoming Exchange 2007 servers.
I don't see any benefit. I just see it adding more complexity and requiring 3 times as many IP addresses.
Without more information, my "best guess" for the recommendation would be with regard to the Microsoft Exchange Server 2007 "Always On" solution. This solution is a clustering solution (CCR) where there is a public network connection (virtual) of the active and passive servers and connection for the heartbeat between the active and passive servers through a private network connection with separate network-addressing scheme.
A couple of links I found that goes into more discussion regarding CCR:
Other than that, I would need more information with regard to the "why" of the recommendation to be of more assistance. Does this help you?
Once adapters are added to a team the IP addresses assigned to the individual ports are no longer relevant. The team's virtual adapter controls the traffic to & from the individual ports. After creating a team, assigning IPs to the individual adapters won't result in any benefit.