I was finally able to get the OpenLayers module working with our Esri map service, using a Web Map Service (WMS); however, WMS will not be practical for use in our base layer (dozens and dozens of layers).

We have a cached map service, using Esri's REST API, that we are using for another web project, and we are trying to take advantage of cached tiles from that server. The WMTS layer type seems ideal, but the Web Map Tile Service was just added to ArcGIS 10.1, and we will not be upgrading from 10.0 for awhile.

Here is a sample URL of a working tile from the REST service:
http://m-map.princeton.edu/Asmobile/rest/services/20130529/Background/Ma...

Our cached map service is at:
http://m-map.princeton.edu/Asmobile/rest/services/20130529/Background/Ma...

The URL for the working map tiles seem very similar to the XYZ layer type, and it seemed like it would work, but the {y} and {x} numbers were completely different (even if I tried transposing y and x). So I started just throwing metaphorical spaghetti at the wall -- although each example URL was slightly different, I tried XYZ, TMS, and OSM. None worked.

Does anyone know if any of the Layer Type options are compatible with Esri's REST service? Or should I ask our map server admin if he can accelerate testing and deploying the version of ArcGIS that supports WMTS?

Thanks,
Michael