It is always good to keep up on Windows Updates but this one is particularly interesting because it is a public release of the newer NT kernel builds. A lot of people won't care about that aspect, but if you have been wanting the BDD XP kernel fix for the NTFS alignment issue, or needing the multi-core XP kernel update, this is your one stop shop for those updates now.
For those tracking the XP SP2 kernel build revisions, it seems to be up to 3093.
Update: I might be wrong on the BDD fix - see below from a comment left from Arian:
This update contains QFE and GDR fixes.
I think a user who has never installed a hotfix he would get the GDR fix which does not contain the hotfix 'branch' as a QFE update does.
So to my knowledge a GDR fix could probably not contain the BDD kernel fix.
So I think it does matter what update a person would get from this public released update.