Apple’s iPhone 4S which is going to be released tomorrow has already been used for a teardown. The cool folks at iFixit have disassembled the entire device to reveal its insides.
The battery in this device is larger compared to the iPhone 4 which is used up to support the all new A5 chip. It has also been confirmed that the device sports a 512MB RAM for increased performance. It appears that additional RAM is not required for Siri, and so it is unclear why the iPad 2 cannot support Siri.