There's an excellent summary at Daniel O'Connor's Catallaxis blog of the physical limits to environmental growth debate. Daniel makes the often-overlooked point that economic growth can arise from physical or non-physical sources (for example, the consumption of more resources or the more efficient use of existing resources). So, to the extent that economists ignore physical limits to the consumption of resources, their analysis is is flawed. But equally, environmentalists who claim that sustainable growth is an oxymoron are not necessarily right because economic growth can occur without additional consumption of physical resources.
Anyway, Daniel explains it much more lucidly than me, so check it out.