Could someone direct me to the release notes for v1.9.4? I currently run v1.9.3, but I'd like to know what has changed before I upgrade.

I looked in the download files, the wiki has notes for 1.9.3 only, and I looked around the forum. Sorry if I missed something obvious!

They are currently missing. You can have some glimpses from svn or RC1 and betas announcements here on the forum. YAF is an open source project and mostly relies on community efforts in things like this.