There seems to be a pretty decent community building visualization tools for Drupal -- there are over 25 projects related to visualization, of which there are several different API modules (Visualization API, Data Visualization API and Google Chart API being three of the best).
This is a topic of interest particularly close to me -- in addition to the Drupal development I do, I'm also a practicing data journalist and am working on a Drupal distribution to enable ManyEyes-like cloud-based dataset and viz hosting. However, as I began building my distribution, I quickly realized that while there are a lot of good tools for Drupal, documentation is sadly lacking and the fragmentation caused by so many separate (and ofter rather-similar) projects means that there is no one "center of gravity".
To this end, I propose to start this general-purpose group in order to advance efforts to create strong, stable, scalable, and easy-to-use visualization tools for Drupal, in addition to discussing the use of Drupal for data visualization more generally.
Note that this group is unrelated to the project of the same name. If this similarity is thought to be too confusing, "dataviz" or even just "viz" is also acceptable.
-Ændrew Rininsland (aendrew)