In case you missed it, last week Microsoft released something they call the Infrastructure Update for WSS 3.0 & MOSS 2007. This update adds some search features to SharePoint that were introduced in the Search Server products, fixes a lot of performance and scaling issues and content deployment fixes. The whole thing is outlined on the ECM team blog:
The Infrastructure Update is not a service pack, but you could almost treat it as one. It includes previous hotfixes, including the ones for content deployment I blogged about previously.
I've seen a few people screw up the install or get confused about it. Here's the deal: make sure you have SP1 installed for both WSS 3.0 & MOSS 2007 (links to it here). Then install the WSS 3.0 Infrastructure Update, run the SharePoint SCA (the configuration wizard you ran when you installed SharePoint... available from the Office Server program group), then install MOSS 2007 Infrastructure Update and run the SCA again. If you've installed hotfixes since SP1, no worries... they are all included in the Infrastructure Update.
I have seen where there is one thing that changed in the SharePoint pipeline and that it has affected [err... broke] some people's code. Dan Larson discusses this in a recent post.
BTW, if you're looking for a single list for where you can see what version of SharePoint cooresponds to a hotfix, or the other in which hotfixes are released, check out Spence's SharePoint 2007 Post SP1 Hotfixes page... a gem for me!