Yesterday, I got to drive US 412 from Alpena to Hindsville and noted the progress on the upgrade west of Huntsville.
The new 4-Lane is approximately 75 percent complete from Hindsville to approximately a mile and a half west of Bus 412 at Huntsville. One side of the new alignment open and striped for 2-Way traffic. The new lane crosses over the old alignment a couple times so it will be the new WB lanes in some places and the new EB lanes in others. The 1947 bridge over Glade Creek has been demolished, though the 2 1930's bridges on "Old (original) 68" are still there.
The other 2 lanes are in the process of being paved, so I'm guessing they other 2 lanes should be open by the end of October, with the exception of the last mile/ mile and a half at the east end, which is still in the dirt work stage.
Google maps also has a partial update for that section of 412 at http://goo.gl/maps/52Nua .
There is also construction along US 412 west of Osage. It appears to be 2 additional lanes beginning at the top of the mountain and extending west to AR 103 North, then becoming 1 additional lane for another mile. This appears to be a fairly new project, having just started in the last few months.