I use a Cingular 8125 and am looking at various phones for an upgrade (I want more speed). In my opinion, a hard drive is a liability for a PDA phone - it adds a breakable moving part that is better dispensed with by increasing the flash memory. I don’t want to replace my phone, I want it to last. Hard drives wont, unless they sit on your desk and don’t get carried around. I have cheap land line phones and a desktop PC for the only situation in which the hard drive is not going to crap out.
That's why the iPhone doesn't have a hard drive... it uses Flash memory.