Last year, Google acquired a data visualization technology from Gapminder, a Swedish non-profit organization. Gapminder's technology, Trendalyzer, was used to visualize data from United Nations Common Database in an intuitive way. To quote from Gapminder's site, "this software unveils the beauty of statistical time series by converting boring numbers into enjoyable, animated and interactive graphics." For example, you could see the evolution of carbon dioxide emissions in a country over time or find correlations between CO2 emissions and the income per capita.
Google probably intends to use this technology to visualize custom data. One of the interfaces that will allow you create your own Trendalyzer visualizations is an iGoogle gadget which creates a Flash multi dimensional chart. The input is a file with the following structure: the first column is the item's name, the second is time, the third is for x-coordinates, the forth is for y-coordinates, and the fifth is the size of a ball. I tried to upload a file that has this structure, but the gadget didn't accept it. The gadget is probably a part of a new service that also hosts your data.
This is not the only data visualization gadget developed. Another gadget creates an interactive table that supports filtering and grouping, the simple table gadget lets you perform queries, while the heat map gadget "displays a map with color intensities that match given values". There are also gadgets for pie charts, column charts, bar charts, area charts, image lines, scatter charts, organizational charts, time series.
Hopefully we'll be able to actually use these gadgets and Google will create a service around visualizing data.
Update: The gadgets are a part of a new Google Spreadsheets feature.