Where / how to get free high resolution satellite images for geospatial data visualization with python

I want to overlay geospatial data (mostly heatmaps) on top of high resolution satellite images using python. (i am newbie, so be gentle on me ;-) )

Here is my wish list

• detailed enough to show streets and buildings
• must be fairly recent (captured within last several years)
• coordinates and projection of images/maps must be known that heatmaps i created can be overlayed
• easy retrieval (hopefully, several lines of python codes will take care of getting right images)
• free

I think google map/earth, yahoo map, bing, etc... could be potential candidates, but I am not sure how to access them easily. Code examples would be very helpful.

Any suggestions?