Thanks for your reply!
SurferTim:
Are you using IDE v1.0.1?
Yes, I've tested compiling/uploading on two machines. Both are running 1.0.1.
Is the shield connected to a router that has a dhcp server?
Yes, it's plugged directly via Ethernet into the router. I've tried two separate ports, and confirmed that plugging other devices (i.e. laptops) into those ports have resulted in the device being issued an IP.
Have you waited a couple minutes for a fail message? Mine takes about a minute.
Indeed, on one test run I just let it go for about 5 minutes while I was doing something else. No further activity beyond the above.
I'm fine with purchasing a new Ethernet Shield if this one's a dud, but I'd like to confirm it's a dud before buying a new shield which does exactly the same thing!