Apple Insider claims to have obtained confirmation and so called additional details from its sources.
The photo would not be showing the battery, and its dedicated space would be hidden by the top part of the case. So the MacBook Pro would then adapt a similar design already used in the MacBook allowing to easily access the HD to change it after having removed the battery. The hole in the bottom case being a latch that will pop-open the battery/HD chamber, representing about 1/3 of the bottom space of the future MacBook Pro.
So, Apple only needs to decide if such design will appear soon, with a future revision of the current MacBook Pro powered by the Penryn, or if Cupertino decide to unveil this new enclosure for the Nehalem-based MacBook Pro which should arrive either for Christmas or for the MacWorld SF in January 2009.
