There isn't much open about S&T's maps and you are stuck with Microsoft's map update cycle for changes.
If you want to integrate
just the maps and your software already has all the necessary functionality, you might be better off to explore open source mapping. Here are some links to get you started:
http://www.openstreetmap.org/ http://opensourcegis.org/ http://www.maptools.org/ http://mapguide.osgeo.org/
Another alternative is to look at the Garmin map format. It's pretty open and well understood. There are loads of people out there creating free maps of various parts of the world and there are lots of utilities to support the creation and modification of the Garmin map format. Let us know if you are interested in pursuing the Garmin possibilities and we can probably point you to some information sources.
With either open source mapping or Garmin format maps, you are pretty much in control of your own destiny. If the users want to submit map corrections to you, you will be able to make the changes as and when you want rather than waiting for a commercial vendor to do it.
With the Garmin format you can do corrections on a transparent overlay so that if your underlying data happens to be from a commercial vendor or other regularly updated source, you haven't messed with the base data. You've just added an overlay that can be changed or removed at your whim. This is probably also true for open source mapping. I'm just not as familiar with the possibilities or the availability of the necessary source map data. You haven't mentioned the locations you are interested in map data for, so it's hard to speculate what might be available. I'm assuming it's North America or wouldn't be interested in Streets & Trips.
...ken...