[Joel]

In Graffle 4.1.2, the autosave information is placed in the resource fork of the file itself, so if it hasn't been saved yet, there's no autosave.

In Graffle 4.2 and later, the autosave file gets saved outside of the file, if the file hasn't been saved the autosave goes to the last save location.

I'd encourage you to go get OmniGraffle 4.2.1, and apologies for the inconvenience this has caused.