The latest hotfix package for Outlook was released this week which resolves many of the .NET item leak side effects in the calendar by changing the behavior of Outlook to not reuse calendar item references in memory and instead reload them from the store.  The KB article calls out a specific scenario of unintentionally saving and sending a meeting request, however, the fix actually goes beyond this scenario and I would recommend it for any .NET item leak problems involving calendar items.

957692  Description of the Outlook 2007 hotfix package (Outlook.msp): October 28, 2008

http://support.microsoft.com/kb/957692

"Consider the following scenario:

•In Outlook 2007, a user has a managed add-in installed. This managed add-in is listening to an Application level event.

•As a meeting organizer, the user sends a meeting request to an attendee.

•Then, the organizer opens the meeting appointment to make some changes.

•After that, the organizer clicks Send Update to try to send the meeting update.

•During the sending of the meeting update, the organizer cancels the send and clicks Don't save changes.

In this scenario, a meeting update is sent to the attendee unexpectedly. Additionally, the changes to the meeting appointment are also saved in the organizer's calendar. "

If you have a .NET Item leak issue involving meetings or appointments, this fix may resolve it.  If you are experiencing such an issue with a managed add-in then you should click the "View and request hotfix downloads" link at the top of the KB article.  Please note, this does not replace the need to properly release references in add-in code.

Steve asked me to link to a post from Ryan Gregg detailing some changes in Outlook 2007 SP 2 Beta.  Here is what Steve wrote…

Ryan posted an article about some changes we're making in Outlook 2007 SP2. The gist is we're changing Outlook's shutdown behavior to always shutdown regardless of whether there are other running applications using the Outlook Object Model. He's looking for feedback on the logic change, so be sure to send him your comments.

The Exchange Development Blog has a new post about the recently released Rollup 4 for Exchange 2007 SP 1.  There are several key changes to Exchange Web Services in this release that are discussed in the post…

“…If you have written code against Exchange Web Services, we definitely recommend that you take a look at RU4. The following are the biggest changes that will be coming in the rollup:

- Item IDs are now returned after MoveItem/CopyItem calls.

- Unknown/unsupported item types are returned as Messages.

- Updating tasks can now have correct behavior for Start and Complete Date values…"