With the launch of Google Docs & Spreadsheets for Google Apps around the corner, I figured it was about time I dug around the source code to see what I could find. I decided "charts" would be a good place to start in Google Spreadsheets -- and boy did I find them. Many brand new references to charts were found scattered throughout the source code.
It wouldn't surprise me if a significant upgrade (that includes charts) is rolled out very soon. You can find references to this coming feature in many of the externally linked files in the source code:
Here is a list of chart types that will be the supported according to the "charts_messages_en" file:
_C = ('Pie');
_C = ('Columns');
_C = ('Bars');
_C = ('Lines');_C = ('Scatter');
Until now, the only reference to charts in the source code was an image named "testChart.png" that didn't even actually exist. I would say this is enough evidence to "get our hopes up".