Now the more interesting case I think has to do with mobile in ERP. These are often shared devices (for example portable data terminals of one sort or another, some of which are even phones too), and even when they aren't, you need some assurance that it's not a kid playing with the device.

Currently the work I have done in this area has been one of two two approaches:

1) The app stores the information and maybe sends it to the user in an email. Copy and paste into a text field in the ERP app, or

2) A traditional username/password login.

In these areas I don't see a better approach. Sometimes even invoices may be entered. You really need to know who is doing it.