Personal Geodatabases are accessed by passing the filename of the .mdb file to be accessed as the datasource name. No ODBC DSN is required.
OGR treats all feature tables as layers. Most geometry types should be supported, including 3D data. Measures information will be discarded. Coordinate system information should be properly associated with layers.
Currently the OGR Personal Geodatabase driver does not take advantage of spatial indexes for fast spatial queries, though that may be added in the future.