Well that'll be 'cos the former was a PDA while the latter is a phone.
Oddly enough nobody ever managed to make PDAs sell as they only appealed to seriously anal business types (i.e. the ones who think having an MBA is actually cool) and geeks with absolutely no life whatsoever.
Mobile phones are a mass market thing and mobile phones that do other things as well are a logical extension.
Biting the hand that feeds IT
