Maply is a 2D and 3D map rendering toolkit for iPad and iPhone based on OpenGL ES 2.0. It lets you put labels, markers, vectors, and shapes on top of an interactive map with one or more base layers of pageable image data.
Check out the video for a quick tour.
Maply is actually part of the WhirlyGlobe-Maply component. The library handles both a 3D globe and a 2D/3D map with different entry points.
Go check out this page for details on how to get the library and use it.