Microsoft Research released a Tiled Vectors Demo which is available for download.  The demo shows a way to solve the problem of showing extremely large mapping data sets in the web browser.  If you have used the Virtual Earth AJAX/JavaScript Map Control or other web-based mapping controls or any web application with a large number of DOM elements/SVG/VML graphics, then you probably have seen that loading extremely large data sets (with thousands of points, lines, and polygons) can bring the browser to a crawl because of limitations in the browser DOM.

The Tiled Vectors Demo from MSR attempts to solve this problem by breaking up the shapepoints into constant-sized sets, similar to how MapCruncher breaks up images into image tiles.  Since the data is broken into constant-sized sets, the original data set can be arbitrarily large -- so the solution scales really well to extremely large data sets.  Regardless of which level of detail you are viewing the map from, the amount of data the map loads is always constant.  This significantly improves performance.  The vector data is still loaded using Virtual Earth VEShapeLayers in JavaScript -- so the shapes are still interactive and can be controlled from client code and respond to events.

You can see a demo page here:

Tiled Vectors Demo

For more detailed information regarding the Tiled Vectors approach and how you can apply it to your data sets, see:

Tiled Vectors Demo Information