It reports usage and your install data to PressTrends. It's VERY easy to miss in the changelog (since v3.4.4). If you don't want your personal information being sent to an analytics company without your consent DON'T INSTALL.
Data being collected:
site URL,
posts published,
pages published,
total comments,
total comments approved,
spam count,
pingbacks count,
post conversion (published posts / published posts with comments),
theme version,
theme name,
site name,
plugins count,
plugin name (wp rss aggregator),
wordpress version