After applying the Infrastructure update on a MOSS 2007 Server with 'GroupBoard Workspace 2007' installed the 'SharePoint Products and Technologies Configuration Wizard' would fail at step 2, with the following error messages logged in the Event Viewer:

The schema version (3.1.3.0) of the database v3_MOSS_SPSUPGRADE_PORTAL_80_CONTENT on VM-SQL\SQL2005 is not consistent with the expected database schema version (3.1.5.0) on SPSUPGRADE. Connections to this database from this server have been blocked to avoid data loss. Upgrade the web front end or the content database to ensure that these versions match.

Database 'SharePoint_AdminContent_9ff3db24-91c8-4b79-9d71-9a8b0e0323bf' on SQL Server instance 'VM-SQL\SQL2005' is not empty and does not match current database schema.

Failed to initiate the upgrade sequence.
Failed to upgrade SharePoint Products and Technologies. Further information regarding this failure can be found at C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\12\LOGS\Upgrade.log.
An exception of type Microsoft.SharePoint.Upgrade.SPUpgradeException was thrown. Additional exception information: The specified SPContentDatabase Name=SharePoint_AdminContent_9ff3db24-91c8-4b79-9d71-9a8b0e0323bf Parent=SPDatabaseServiceInstance Name=SQL2005 has been upgraded to a newer version of SharePoint. Please upgrade this SharePoint application server before attempting to access this object.
Microsoft.SharePoint.Upgrade.SPUpgradeException: The specified SPContentDatabase Name=SharePoint_AdminContent_9ff3db24-91c8-4b79-9d71-9a8b0e0323bf Parent=SPDatabaseServiceInstance Name=SQL2005 has been upgraded to a newer version of SharePoint. Please upgrade this SharePoint application server before attempting to access this object.
at Microsoft.SharePoint.Upgrade.SPSequence.get_CanUpgrade()
at Microsoft.SharePoint.Upgrade.SPManager.CanUpgrade(Object o)
at Microsoft.SharePoint.Administration.SPPersistedUpgradableObject.get_CanUpgrade()
at Microsoft.SharePoint.Upgrade.SPManager.ReflexiveCanUpgrade(Object o)
at Microsoft.SharePoint.Upgrade.SPManager.NeedsUpgrade(Object o, Boolean bRecurse)
at Microsoft.SharePoint.Administration.SPPersistedUpgradableObject.get_NeedsUpgrade()
at Microsoft.SharePoint.Upgrade.SPManager.Initialize()
at Microsoft.SharePoint.PostSetupConfiguration.UpgradeBootstrapTask.Run()
at Microsoft.SharePoint.PostSetupConfiguration.TaskThread.ExecuteTask()

Workaround:
Uninstall 'GroupBoard Workspace 2007' and re-run the 'SharePoint Products and Technologies Configuration Wizard'.

According to this article: http://blogs.msdn.com/sharepoint/ we should:

"If you are running SharePoint Server 2007 you should install the Infrastructure Update for Windows SharePoint Services 3.0 (KB951695) first and the Infrastructure Update for Microsoft Office Servers (KB951297) second."

This doesn't appear to be mentioned in this article...

Is it required or not?

@Mark Fendley

Yes you have to install the WSS update first then the MOSS update. You can skip the Config Wizard until after the MOSS update finishes.
That's correct, install the WSS update first. We recommend that you skip the Config Wizard for the WSS version. Thanks for your feedback. Expect an update to this article soon.

Can you Slipstream the SharePoint 2007 SP1 by putting both Infrastructure Updatres in the Updates folder of SharePoint. Your articles do NOT...I REPEAT...DO NOT suggest that this is required or even possible.

Joel: This Article or another should be updated to clarify that the folder while it works, has not been tested to deploy the Infrastructure updates or future hotfixes. So you won't find support for this method. I'd love to see documentation supporting it, with the testers with the understanding that this will be how people install new servers and farms to simplify deployment. (especially in W2K8 new deployments)