Social Gold is the same company I got that graph of highest spenders from.
I also can't believe 41%, unless maybe it's saying that they've found one game where 41% of users who buy something once make a second purchase. I couldn't find this stat on their site right off, but poking around a little on their blog turned up
this post that has some pretty plausible claims along those lines.
Honestly, I think they're trying pretty hard to knock off
OK Trends but don't have the stats background for it.