Two weeks, though, is what it took for the Mac Business Unit to get a tested patch out the door that resolves this problem. Today, Product Manager Andy Ruff announced on the Mactopia support forum that Office 2008 12.1.4 is now available for download (16 MB, requires 12.1.3 installed), billed as follows:
This update fixes a calendar issue in versions of Microsoft Entourage that were updated with the Microsoft Office 2008 for Mac 12.1.3 Update. The issue prevents Exchange accounts in Entourage from sending meeting invitations and responses. This issue can occur when an Entourage identity is configured with more than one mail account. We strongly recommend that all Entourage users who installed Office 2008 for Mac 12.1.3 Update install this update.
While this particular fortnight may have been difficult for Entourage users, I will say that this is definitely the fastest response to an Office bug that I have ever seen from the Mac BU; in terms of the development cycle on a suite as large as Office 2008, it's an eyeblink. Kudos to the MBU for its quick action; now, the next prudent PR step is a little bit of transparency about why this bug -- which should have been fairly obvious to anyone who tested with both Exchange and POP accounts configured in the same identity -- managed to make it through to the release.
Update: Wow, talk about your rapid response... Andy has posted an explanation of the issue and the testing circumstances at the Mac Mojo blog. The missing piece of the puzzle, apparently, was account creation order: if the Exchange account was added to Entourage after the POP or IMAP setup, the problem got triggered -- a condition that never made it onto the testing radar. Points for transparency: awarded.