Depends on the shop, and the needs of that shop. If your development necessitates that you run one or more virtual machines on a consistent basis, the 8GB memo

Depends on the shop, and the needs of that shop. If your development necessitates that you run one or more virtual machines on a consistent basis, the 8GB memory limitation of most laptops bites your hand almost immediately. If you work on VLDBs, the lack of storage and I/O bites your hand almost immediately. If your developers largely don't need to be mobile, you're paying a significant premium for mobility and sacrificing power when those sacrifices aren't necessary. If you develop games or iPad applications, the lack of display real estate annoys the crap out of you almost immediately. Different strokes for different folks.