Not yet searchable or in the TOC, but here are the direct links:
Understanding Load Balancing in Exchange 2010:
http://technet.microsoft.com/en-us/library/ff625247.aspx
Load Balancing Requirements of Exchange Protocols:
http://technet.microsoft.com/en-us/library/ff625248.aspx
Cheers,
Henrik Walther
Technology Architect/Writer
MCM: Exchange 2007 | MVP: Exchange Architecture
MCITP: EMA + EA | MCSE: M + S | TechNet Influent