The site is reporting that the S3 will be motivated by a 2.0 TFSi engine producing 260 horsepower. Volkswagen/Audi currently use this engine in various forms across their model lineups. The Audi A4 S-line Special Edition currently has the most powerful version of the 2.0L TFSi engine that produces 220 horsepower. That engine employs different pistons, a modified turbo and new ECU to achieve the bump, though it's not clear how the S3 will squeeze out an additional 40 horsepower.
The A3 is also offered with the company's 3.2L V6 engine that produces a healthy 250 horsepower, so it seems odd that the S3 would feature a four-cylinder working much harder to make a few more ponies. Perhaps the fuel savings afforded by the four-cylinder are significant enough to warrant its use.
The S3 will also have Audi's Quattro all-wheel drive system and is visually distinguished by a different front end, larger alloy wheels and dual exhaust pipes. Clearly the model pictured is meant for European markets, so we'll have to wait for its debut overseas before we learn more about U.S. availability.