Comment 6 for bug 92338

 On more careful reading of this bug (#92338), it seems to be reporting the problem that your main network interface can't be in /etc/network/interfaces if you want to boot with nfsroot. The fix for that is support for the "manual" setting in interfaces(5) to stop ifupdown breaking the nfsroot. e.g.
auto eth0
iface eth0 inet manual

 So I was wrong earlier, and this isn't a dupe of bug 268005, even though they basically cause the same problem. I had been going to send email asking why you closed this even though it was still a problem. But as I discovered, this bug is fixed, and the regression in n-m in Intrepid is a different problem.

 I'm pretty sure bug 268005 will be a problem for nfsroot in general, not just boot=casper. It prevents nfsroot netbooting the Ubuntu Intrepid alpha6 live cd (except with a workaround hack).