as for .22, nope. pistols must be able to make power factor. IDPA is based on defensive carry pistols. .22s are not strong enough to stop a bad guy reliably under stress. Hand loads must be able to make a certain power factor too, so that people don't run really weak ammo for quicker double taps etc.
9mm is most common, as its cheap and readily availiable. you can get old surplus guns in 9mm, you can get 1911s in 9mm and you can even get revolvers in it. As well, of course, many many modern guns in 9mm.