Actually, that's the "Art History Brush Tool".
QUOTE
Like the History Brush tool, the Art History Brush tool uses a specified history state or snapshot as the source data. The History Brush tool, however, paints by recreating the specified source data, while the Art History Brush tool uses that data along with the options you set to create different colors and artistic styles.
--snagged from the Adobe Photoshop CS3 help files. RTFM guys.To understand this, you're going to need some basic knowledge of PS here. Specifically, what "snapshots" are in the History list. A Snapshot is just a "picture" PS keeps (on your instruction) of the STATE of a PSD. What the picture looks like at that point (including layer properties, channel settings etc). What the History Brush Tool does, then, is that it paints using the selected snapshot as a reference. It restores the portion you paint over, to the state found in the Snapshot.
The Art History Brush Tool just adds... let's say
filters to the restorative properties of the Art History Brush Tool.
Think of it as... a stylized and brush stroke specific undo. After a fashion.