The Press-Gazette does offer some new details:
The NFL allows teams a third uniform, following a year-long approval process, that they can use up to three times a season – twice at home and once on the road – for a five-year period. The Packers will have only a home version of the new uniform, and Murphy said they probably will use it only once this season against a yet-to-be-determined opponent.That's great news. But so is this:
Murphy would not describe the uniform except to say it’s from the team’s first decade – the Packers started playing in 1919 and joined the NFL in 1921. The team will unveil it Friday, with several players modeling it during Fan Fest’s kickoff, which begins at 4 p.m. at the Lambeau Field Atrium
"Those people that remember the history and follow the history of the Packers, this was a pretty successful era for the organization," Murphy said. "It was also finding something we hadn’t done before that we thought fans would be able to appreciate and allow them to celebrate the great history and tradition of the Packers."I couldn't agree more. Bravo.
UPDATE: The Packers have also confirmed the report on their site:
Third Jersey To Be Unveiled Friday At Fan Fest