To export Exchange 2007/2010 tracking log to a Excel, just run this command.
get-messagetrackinglog -Start “31-08-2010 00:00:00” -End “01-09-2010 12:16:00″ -resultsize Unlimited | select-object Timestamp,ClientIp,ClientHostname,ServerIp,ServerHostname,SourceContext,ConnectorId,Source,EventId,InternalMessageId,MessageId,TotalBytes,RecipientCount,MessageSubject,Sender,ReturnPath,@{Name=”Recipients”;Expression={$_.recipients}},MessageInfo | Export-Csv
It will export all mails from 31/8-2010 to 1/9-2010, with the selected fiels.