It wont effect the overall specs of the system.
They're now going to start using the 65nm manufacturing process instead of the 90nm process.
Less power usage (hopefully, no more 'brick'!), and signifigantly less heat output.
-Other 360 Pre-E3 rumours... The HD-DVD add-on drive will be out in September (still no pics or pricing until E3), and there will be a price drop for the premium and core systems come October - Perhaps as much as $100 off the Premium bundle.