Looks pretty useful-- the marker bar view has actually been part of Eclipse and XCode for ages (and I'm sure some other IDEs implement it too), but I haven't seen a thumbnail view before-- that could be pretty handy.
If they want extra points, they can make the marker bar view actually line up with the scroll bar (Eclipse's bar doesn't line up with the scroll bar, which can be annoying, and XCode's view is inside the scroll bar, which means any markers inside the current view are completely hidden).