This one takes some rather esoteric physics tricks. The idea is that if you enter an angled plate portal straight down, you will come out of the other portal at an angle.

I provide walkthroughs for all my test chambers that aren't in the Experiment series. This one's walkthrough is at http://www.youtube.com/watch?v=wAUKdNQmBAc&feature=player_embedded . It's also embedded on this page, with the screenshots.

I can ony get the first cube, the last two either get me thrown back onto the platform where I found the first one, or I simply don't gain enough height.