Many (including myself) have reported that side by side the iBook G4 had a better reception and range of wireless networks than the PowerBook G4. This was reported to be the case due to the construction material of the machines. I have not read any reports about the MacBook Pro but it’s being reported that the MacBook has the best range of all tested Apple notebooks, even the iBook G4.
Apple have redesigned the wireless antennas on the MacBook which they have placed horizontally on the left and vertically on the right, specifically for that model. The reception and range is reported to be such an improvement that some users are picking up networks they didn’t even know existed using other models in the same area.
Officially Apple say the MacBook only supports the wireless standards of 802.11b and 802.11g, however it appears to be connecting flawlessly with 802.11a also.