This is an interesting reversal of branding. When the unibody MacBooks were released last fall, they appeared nearly identical to the larger, "Pro" labeled companion. The two big differences (aside from screen size) were the video card configurations (integrated for the MacBook, as opposed to integrated and discrete in the MBP) and the lack of a FireWire on the "amateur" edition. Many of us speculated that the removal of FireWire was done primarily to distinguish between the two lines and try to move consumers up to a pricier model.
There was a lively debate in the posts about FireWire's exodus from the unibody MacBook about what constitutes a "pro" machine from something that shares the same design but is smaller in size. Without rehashing the whole debate, it pretty much mirrored those "my dad is richer than your dad" fights that always seemed to break out at high school parties in my district. In my experience, when arguments essentially become "you're only a pro if the label says so," the real-world distinction is gone.