From Jayski.com:

Scott Speed to NASCAR? Axed Toro Rosso racer Scott Speed will almost certainly switch to the NASCAR series in 2008, it has emerged. Although his relationships with STR chiefs Franz Tost and Gerhard Berger are over, the Californian remains strongly linked with Red Bull magnate Dietrich Mateschitz -- who also owns a new team in the premier American tin-top category Nextel Cup. "Speed drove in Formula One against the world's best drivers," the Austrian billionaire is quoted as saying by Motorsport Aktuell, "he is courageous, and his name is a marketer's dream -- and with a cowboy hat it is perhaps complete!" Team Red Bull is a works Toyota-supported NASCAR team. "He would be an asset for us in NASCAR," Mateschitz said of the 24-year-old.(Yahoo UK), it doesn't say of it will be for Cup, Busch or Trucks or if Speed would replace Vickers or Allmendinger or that Red Bull would add a 3rd team for Speed.(8-14-2007)

AND: Formula 1 racer Scott Speed will switch to NASCAR in 2008, according to sources at Red Bull Racing [once again, it doesn't say which series]. The California native made his debut in Formula 1 in 2006 and competed this past season, but was released from his Toro Rosso team last week for lack of performance. Since his debut with the team in March of 2006, Speed failed to score a championship point. Red Bull owner Dietrich Mateschitz who sponsored Speeds Formula 1 team also owns a the Nextel Cup team with Toyota drivers AJ Allmendinger and Brian Vickers. Mateschitz told a German language motorsports website Tuesday that Speed Would be an asset for us in NASCAR. According to the same sources, the team will drop the Toyota brand and switch to Chevrolets in 2008 as well [which has been denied].(Cup Scene Daily)(8-14-2007)