A nice venn diagram would show us exactly where we can put all our technologies.
I’ve done that here at home but the results are simpler to show in text form.
We start with our mobile device. We want everything possible on this device and we have a device no bigger than 3″ with a numeric or thumb keypad so you can forget video and decent input mechanisms. Efficient browsing is also out of the question.
You can put the following on your mobile phone device:
Mobile phone voice
Mobile phone non real-time Instant Messaging (SMS/MMS)
Calendar
Contacts
Reminders/To-do
Digital Camera (2mp with good optics is the entry point for useable photos)
Document storage (local, up to 4gb today.)
Music playing/recording.
Simple video clip recording/playback.
GPS navigation.
Device control – (Consumer infra red) (although I havent seen this on many phones)
Data gateway. (Bluetooth with GPRS/UMTS is the most sensible choice but wifi is also bossible.)