You really think you'll miss that extra FW port? I generally dont use more than 1.
On the Macbook there will be no FW port, just two USB ports.
On the Air still one USB Port and I am always slightly concerned about having just one port (though it may be also just one bus on the MacBook also). I prefer having two just in case.
On the MacBook Pro they removed the FW400 and just left the FW800, but not a huge issue to because of the Express Card slot.
As to not having FW, it is becuase of extra hard drives and more so video camera capture when travelling. The weight drop, better video card and the other improvements does make the MacBook tempting otherwise to me.
If they knocked some weight off the 15" it would have been nice, but the specs seem to indicate the same weight. Prior to the updated MacBook the 15" and 13" were rather close in weight so the 15" seemed to be more worthwhile.
The life of diving and trying to cut weight and size to get all the toys you need 