Check the American Rifleman about six months ago. They had a very thorough article about the .45 Super. Ammo is available from Triton, and brass from Starline. Kits for conversion are available from Ace's Custom Guns (the developer), and completed guns from Ace's, Springfield Armory, and others.
The H&K USP, and the S&W 625 revolver can handle .45 Super without modification. Every .45 Super can also handle .45 ACP without modification.
Ace's is the shop which developed this propriatary round, so contact them for more info. Hope this helps, Walt Welch