On-Device Portals is an industry in hunt of a definition…WirelessWeek has a good overview of the players, but what distinguishes it from mobile apps? Not much in my opinion. In essence, they are branded mobile apps, and in most cases, a closed ecosystem at that.
This is primarily a vendor-driven definition, and had very little traction in the content industry.

Examples include apps from Handmark, which sits on Sprint Nextel’s deck, among others. Others point to Alltel Wireless’ Celltop, Yahoo Go and Apple’ iPhone as examples of ODPs. Some have even suggested an ODP as an alternative for brands to act like an MVNO without all the hassle of becoming an MVNO, the WW story says.

A whitepaper defining it is here (PDF link).