I applied the MOSS infrastructure upgrade w/o applying the WSS one before it -- uh, help!
Sounds like time for a full restore. The MOSS upgrade steps did explicitly ask for a restore, didn't it?
I believe that is a supported, but unrecommended configuration. You should be able to get help from microsoft :)
Quoting: Infrastructure Update for Microsoft Office Servers (KB951297)
Other Relevant Updates It is strongly recommended that you install the Infrastructure Update for Windows SharePoint Services 3.0 (KB951695) before installing this update on any of the Office Servers listed in the system requirements section above.
Therefore not applying first Infrastructure Update for WSS seem to be not recommended but not unsupported
The TechNet article Install the Infrastructure Update for Microsoft Office Servers (Office SharePoint Server 2007) has a dicussion on this in the community content section. Someone commented that the WSS update must be run first. There is no suggestion for what to do if you don't or what the consquences are.
I am assuming that you have also run the Configuration wizard after you applied this and brought your system online? If you have not, you are in a much better position, as you can apply the WSS upgrade - then run the wizard and you should be fine.
If you have run through the wizard - and brought the system back online - its not the end of the world. What you will want to do - is go back and follow the steps to upgrade your system just as if you had not done anything. The infrastucture update makes some significant changes and improvements to portal search - so once you start trying to configure that, you'll see some errors in crawling etc - as the indexer (which has been updated) tries to crawl content (which has not).
Apply the WSS bits, then reapply the bits for MOSS, then run the Config wizard and bring everything back. You should be okay at that point.
Obviously, before you do anything, backup all systems and take them offline.
Hope this helps.