Will Exchange 2007 in a multiple forest environment allow the viewing of calendars across forests. With Exchange 2003 and using MIIS 2003 this is not possible and I wondered if it would beocme available with Exchange 2007 and perhaps an updated MIIS. Thanks

You can do this with Exchangew 2007, more information can be found here: http://exchangeninjas.com/AvailabilityServiceFAQ As for MIIS 2003 and Exchange 2003, you can do it if you add in the InterOrgReplication tool to replicate the FB folders. This provides simple Free/Busy information to be shared across Orgs but does not give appointment details. http://support.microsoft.com/kb/q238573/