Mobile integration

Hi Experts

We want to have SAP application of Purchase order creation / change / deletion scenario in Mobile (PDA / iphone /Blackberry).

Kindly suggest how this scenario can be brought in mobile and how it can be integrated with SAP logistics module , is this

scenario can be built up using standard netweaver application or need third party application.

Assume somebody might have come up with this scenario and using it , If yes please share on details.

Thanks in advance.

PP.