>There are some industries where pda systems are rapidly overtaking PC-based solutions- so much so that PC systems might reasonably be regarded as "dead".

I think PCs are here to stay but there will be internet devices and PDAs as alternatives. Check out www.pocketpc.com. Really 90% of the people use a computer for Email, Web and word documents. A pocket pc (PDA) does all this.

>Is a PDA app C/S?

Yes. PDA are just small computers. You can write VC++, VB, Java or browser code that accesses a back-end database.