Sorry, but I'd blame your prerelease WebKit build.
I can't recall ever seeing AJAX eat a post and I do virtually
all of my posting and editing through the inline AJAX controls.
Fortunately, I don't use the WebKit nighties for much of my browsing.
If you turn off JavaScript in your browser, that will disable the inline AJAX and use good old fashioned get and post requests. If you want an AppleNova-specific toggle, err, I'll have to look into that.