I don't think the Green Bay Packers really wanted to enter the 2012 season with Marshall Newhouse as the only experienced, healthy left tackle on the roster. Despite their faith in Newhouse, his concussion (and it could keep him out a while, the recovery time is different for everyone) has exposed the lack of depth at offensive tackle.
The only way the free agent adverse Packers would have added veteran depth was if Chad Clifton returned healthy, but that dream ended when he failed his physical in April and he was released. It's possible he could come back in 2012 and I recall reading somewhere that the Packers were initially pleased with Clifton's recovery. The Packers have re-signed players months later, once they're healthy; that's what they did with Anthony Levine last season. However, his likely desire to start makes his return seem less likely.
They probably expected Derek Sherrod to return to practice by now, though he's still not ready. Fortunately, he should return at some point this season. After using two consecutive first round selections on offensive lineman, I can't blame the Packers for avoiding the position in the 2012 draft. They did select Andrew Datko in the 7th round, and he looked good during the OTAs back in May, but reality has set in and he's getting overwhelmed in practice. He doesn't appear to be 100% recovered from a serious shoulder injury during his senior season.
Until Newhouse returns, it's Herb Taylor with the No. 1 offensive line, but even Mike McCarthy didn't seem too excited about Taylor's prospects when he called him "raw" despite the Packers being his fourth NFL team. Taylor is probably their fifth option (behind Newhouse, Clifton, Sherrod, and Datko) but they probably would survive with him at left tackle. However, if Newhouse and Sherrod don't return soon, I don't expect the Packers to stand pat.
GM Ted Thompson has been known to make a trade or two at the end of the preseason, and I wouldn't be surprised if this season's no exception. After they've scouted all the preseason games around the NFL, they could trade a 6th or 7th round draft choice for a tackle that could help them now.