MacBook sales explode; 15-inch version due?

DigiTimes is reporting that sales of Apple's Intel Core Duo-powered MacBook notebooks are exceeding initial estimates:

Sales of Apple Computer's Intel Core Duo-based MacBook laptops have been stronger than expected, boosting monthly shipments of 13.3-inch MacBooks from Taiwan-based Asustek Computer to about 120,000 units in June, up from about 100,000 units when the company started shipping the new computers in April, according to sources at Taiwan-based notebook makers.

I'm not surprised that the MacBook is doing well in the market. Pound-for-pound the MacBook probably has the best price performance ratio of any Mac ever released. At US$1,100 the MacBook is a steal. The most interesting part of the DigiTimes story is embedded in the last paragraph.

Sources contacted by Lin also noted that Apple may expand its MacBook family by introducing a 15.4-inch widescreen lineup, although the market has expected Apple to launch 12.1- and 14.1-inch MacBooks to replace similar-sized iBook laptops.

A 15.4-inch (non-Pro) MacBook might cannibalize sales of Apple's higher profit MacBook Pro -- which retails for about US$1,000 more  than the consumer-oriented MacBook. Apple would be better served to leave the 15 and 17-inch models in the Pro space and introduce a 12-inch MacBook for users on the go. The only problem that may be holding back a 12-inch MacBook is heat. Remember how hot the 12-inch PowerBook G4 runs? I can't imagine that enclosure with an Intel Core Duo chip in it. Can you?