I supposed this isn't especially pertinent because my application would be refused if judged by the newest rules, but I just got my Post-Study Work visa today from Sheffield after about seven weeks of waiting.
What is strange is that I called the UKBA two days ago and was told my application was still pending, even though it was actually processed by the 8th of May. Just goes to show how useless it is to call them!
Anyway, thanks for the helpful advice, UKYankee (esp. Vicky). I don't think I would have made the deadline without the information I found here.