Maptimize have released a preview of Maptimize Version 2, in the form of CrunchPanorama. Here is Maptimize's description:

CrunchPanorama is powered by the next generation of Maptimize engine.

Much more than a clustering server-side engine, the new version of maptimize is a real-time search engine for online maps. Crunchpanorama shows some of the new features.

You can

• set any meta data to markers. For example, in crunchpanorama, you add creation date, number of employees, categories...
• filter in real time the map using your meta-data, like number_of_employees > 10 and category = "web"
• get any information on cluster still using your meta data like average, sum, min or max and use them to display cluster information.
• customize the rendering using your own markers as you do on regular maps.

Maptimize is available as SaaS and as a standalone server.

The demo has a nice slider that lets you view company data for a range of years. Clustering and company counts interactively vary with this slider. Clustered data can also be updated interactively using checkboxes (eg. company type). Great in principle, although I found it a bit slow for my tastes. I suspect a client-side solution is the only way of providing these data updates fast enough.

CrunchPanorama can be viewed at http://www.crunchpanorama.com. Further information can also be found on the main Maptimize website.