Google's heat map and motion chart in comparison

In addition to the motion chart (reviewed here), Google announced a heat map gadget. It's quite easy to use just like the motion chart. That is, the most difficult part is to collect data for the chart in the right format.

The following heat maps display two variables, the median age (years) and the unemployment rate (%), of countries by using colors on the world map (data source: CIA's World Factbook).

How useful is the heat map concept? Is it a good infographic?

It depends: If your target is to visualize every single variable clearly, the concept works. If your target is to help your audience understand the relationship between variables, then an XY chart works better (such as Google's motion chart--here without the animation):

Let's analyze: By average, the lower the median age is in a country, the higher the unemployment rate.

UPDATE (Thursday, April 17, 2008):

Included below a more traditional chart to display the relationship between median age and unemployment rate. In this chart, countries are grouped in median age groups. An average unemployment rate is calculated for each group.