By Gravity, are you talking about Grav? If so, there are a LOT of screensavers out there like that. The best I've seen was on a mac. As for it being a duplicate of yours though, I highly doubt it.
The author is mentioned in the documentation: Greg Bowering.
Registered Linux User #371168
+Fedora Core 3 - k2.6.10-1.766_FC3