Heat map App for Google or Yahoo Maps

I'm looking to have a heatmap generation tool I can use to overlay on top of Google or Yahoo! maps. I'm open to using gheat as it'll probably be the quickest and cheapest way to accomplish this project. I'd like to run this script on the Google App Engine for Python. Part of the requirements will be install instructions for the App Engine. I'm open to alternatives to gheat as well. The app must be able to support 200k lat/lon records.