What mobile device have you owned for the longest? I think its an old Psion for me which I still have somewhere.
I still have my US Robotics Palm Pilot Professional, and the Sharp IQ Electronic Organiser that I owned before the Palm too.
Phone is iphone 4 at 16 months.
Tablet is ipad 2 at 15 months.
Pda is my lovely Fujitsu Siemens n560. Still better at playing games on it than new machines.
Ipod Touch 2g. Must be 2-3 years.
I tend to keep most of my old devices. So old Psion 5 and famous SE. P800
Loox 720, although I gave it away a year or so ago.
My Palm V is my oldest piece of kit, still in mint condition but sadly won't accept a battery charge anymore.
Looking back over my many devices, I've used my iPhone 3GS for 26 months. I would have upgraded, but was unemployed for that time (come on iPhone 5).
The next longest was my Newton MessagePad 120 which I used for 25 months.
Probably my first Palm, Palm IIIc. About 4 years. The iPhones get updated every two years and so far the iPads every year.
I've had my iPhone 4 since day 1 of it's UK release almost two years ago. That's about 6 months beyond my average for my last few devices. No intention of changing it before the iPhone 5, and possibly not even then. It still feels like a shiny new phone to me.
I've got a near mint Palm Centro in it's box with all the bits that must be, blimey 5-6 years old at least. Been meaning to get rid for ages, but haven't the heart, though it hasn't been out of it's box for about 3 years!
Also got a boxed Asus Eee, which I actually bought off a PDA247 regular (Alloafan) several years ago. Rarely gets a look now, but have played with it loads, including installing Windows XP, and Ubuntu on to it.
Again, anyone can give it a good home, as it's just cluttering up my shelf now....?
The oldest working device I still have is my 10-year old Palm Tungsten T (working). My slightly older Samsung SPH-N200 technically still works although it won't function on my carrier's network anymore (except MAYBE 911 emergency calls). Everything else older I sold.
I still have a Palm TX which works and everything, but I never use it. The device I used the longest was my Psion 5MX. I had to get the screen cable repaired once, and the second time it broke I left. But I used that for many years.