Potential impacts to developed areas on or near the coast are of primary concern, but storms like this can also have major impacts in the mountains.
The 0600 UTC 26 Aug forecast from the NAM has one of the more eastern storm tracks and puts the low center just off the northeast Massachusetts coast at 0300 UTC 29 Aug (11 PM EDT Sunday 28 Aug).
In this forecast, the eastern Green Mountains of Vermont, White Mountains of New Hampshire, and various ranges of western Maine are squarely in the crosshairs at this time. However, there is some uncertainty in the storm track as noted in the NHC forecast above, so a pinpoint forecast is not yet possible.
In any event, it is likely that some mountain areas of the northeast United States are going to see heavy rain and high winds, bringing the prospects of flooding, landslides, and blowdown.
In At the Mercy of the Mountains, Peter Bronski describes some of the impacts of Hurricane Floyd on the Adirondack Mountains of upstate New York, including widespread blowdowns and eighteen landslides.
Two of the landslides generated by Floyd were on Wright Peak, opening up prime backcountry ski terrain on one of the Adirondack "high peaks." Unfortunately, one of the slide paths served as the site of New York State's first-ever backcountry avalanche fatality the following winter.
Time will tell where specifically Irene will strike, but it is likely that she will have some major impacts somewhere in the northeast mountains.