I was... since the post didn't give a link to any description of the actual weapons system in the apparently random "that looks neat, what is it" picture, I had to go by pure guess-work... and it didn't look like the barrel/chamber length was long enough to both provide sufficient length for properly concentrated gas expansion and extra rounds, so I had to guess.
Now that I have searched on-line for myself, I found that the pictured item apparently has 6 rounds per barrel... and is 40mm... both facts which were unavailable from either the post or the pic.
http://www.thefirearmblog.com/blog/2010/03/16/metal-storm-and-irobot-team-up/
However, I tend to agree with this poster on that blog:
http://en.wikipedia.org/wiki/Mk_19_grenade_launcher
The Mk 19 looks to be about the same weight and bulk as the MSiR shown, and is already in mass-production.
Therefore, you could mount an existing fully-auto Mk 19 on that robot, and have something that is just as effective in a real-world situation.
Everyone raves about the "up to 1 million rounds per minute" claim... but ignore the fact that that is "cyclic rate" (the rate the weapon could fire at with an infinite ammo supply and no malfunctions), with the sustained fire rate (includes reload times, etc) won't be a lot faster in reality than current weapons, due to the larger and heavier "loaded barrel" system.
Yes, that looks impressive and "kewl", but in reality the need is for precisely aimed and effective fire, not indiscriminate mass fire area destruction... we have much better ways to do that if desired.
Then consider something else... recoil.
vitalis6969 mentioned pistols that can fire 1 round or 36 rounds (all rounds in all four barrels) per pull of the trigger.
Do you have any idea just how massive that recoil would be, and how uncontrollable the weapon would be during firing?
Yes, I know the rounds go off really fast, but even so, the weapon would no longer be aimed at the intended target for at least half the rounds.
To me, this would make such a pistol dangerous and impractical.