I'm so glad you brought this one up. Here is a link to a Guardian article describing the experiment:
theguardian.com - Scientists find antimatter is subject to gravity
What to me is the most amazing thing about the experiment is that they were able to create anti-hydrogen. This means they produced some positrons (i.e. anti-electrons), some anti-protons (protons with negative charge), then managed to get these two sets of very easily destroyed particles to combine into atoms, and then managed to keep these incredibly rare atoms in a magnetic bottle long enough to decide that more of them fell out of the bottom of the bottle than fell out of the top of the bottle. A true tour-de-force. I would have been really surprised if anti-matter hadn't reacted to gravity identically to matter but having created anti-atoms you might as well do something clever with it. I guess they have also done some spectroscopy experiments (e.g. the Lyman alpha emission line) so this may be a natural fall-out (so to speak) from those experiments. Very cool science.

Rgds,
HH/Sean