That seems to be the gist of this article on Pitt’s announcement regarding future non-con games for the football program.

“As our program got stronger, we wanted to shift our scheduling philosophy to meet our strength,” Pitt athletic director Jeff Long said. “We’re a strong program, and we believe we’ll get stronger and should be playing stronger non-conference opponents.”
…
“We’re pleased we have some top-level Big Ten teams on our schedule.”

At the end of the article the future non-con games through 2010 are set out. It would appear that Bowling Green was pushed from 2006 to 2008. Not exactly sure what happened to the Navy game in 2006, but Navy doesn’t have Pitt on their 2006 schedule either.

Here’s the Iowa press release on the announced series.

“We’re extremely pleased to announce this series with Pittsburgh, a respected University with a strong and rich collegiate football history,” said Bowlsby. “There’s no question this is a series that will excite fans from both schools.”

Iowa’s Head Football Coach Kirk Ferentz was also pleased with the four-game series.

“I spent a great deal of my early years in Pittsburgh and still have many family members in the area,” said Ferentz. “I look forward to playing Pittsburgh and the challenge they’ll present.”