Patches for your Holiday Maintenance window..
In this article I discussed a bug with .NET 2.0 that could cause that Exchange Server 2007 to consume too much memory. Now, there is a somewhat related patch that often impacts Exchange and SQL servers. KB 938486 contains a patch against Windows Server 2003 sp1 or sp2 that corrects a situation where a server appears to hang when a process running on the server makes a large memory allocation request. You can either call PSS to request the patch or request the patch online at the link available in the KB article.
Both are recommended for your Exchange Server 2007 servers.
You may remember the issues with Windows Server 2003 sp1 + the scalable network pack (included as part of sp2) and how they negatively impacted Exchange. This issue was documented here and especially affected NICs using the TCP Offload Engine (TOE) capabilities of the NIC (enabled by default in sp2), very specifically using a feature called TCP Chimney Offloading. Broadcomm has finally released new drivers to correct those problems. They are available here. The various vendors using the Broadcomm NICs will likely move the new drivers into their packages, but you can get them more quickly from Broadcomm directly.
Another fine patch to test and install!