We got a letter from the NPS yesterday that will probably be of interest to a lot of board members (and lurkers).
Here's the page I made for this on my shop's site: http://www.parksflyshop.com/roadwork.htm

Long story short, the Gibbon Canyon Road is going to be closed completely starting August 17 for a full reconstruction. This is the short route between West Yellowstone and the NE corner and Yellowstone River fisheries and between Gardiner and the Firehole, Madison, and Old Faithful. Travel times between Gardiner and West are normally about 1hr 15minutes if traffic and bison jams are normal. Now it'll be more like four hours.

In practical terms, this means that if you want to fish the Lamar, Soda Butte, Slough, Yellowstone, Gardner, Grebe Lake, or small streams in the area after the 16th, you should plan on staying in Gardiner, Livingston, Emigrant (Chico Hot Springs), Mammoth, Roosevelt, Canyon, or Lake. If you want to fish the Firehole, Madison, Gallatin, lower Gibbon, or any of their tributaries, and if you want to visit Old Faithful, you should plan on staying in West Yellowstone, Big Sky, at Old Faithful, at Madison Campground, or at Lake or Canyon. Only Lake and Canyon are even remotely centrally located.

In general, this construction means you will have more fishing opportunities before mid-September staying in the northern part of the Park. From then until about the fifth of October it will be a wash. After that staying in West or at Old Faithful will present more opportunities. There are certainly places in the Park around West that fish well before mid-September (chiefly the Gallatin drainage) and places to fish around Gardiner after the first week of October (chiefly the Gardner and the Yellowstone in the canyons), so check with your favorite outfitter to determine where you ought to stay.

If you're doing the tourist thing or want to fish a lot of different water (esp after mid-September), I'd suggest staying part of the time in the northern part of the Park or in Gardiner and then shifting to West Yellowstone (or vice versa), as the drive (and the tourist spots along the way) makes sense if you only have to do it once.

What this is probably going to mean for me are more trips until late September and less competition in my area while guiding them (four hours from West to the Lamar after 8/16), but lots less trips in October as the Firehole is our #2 destination in October after the Gardner. On the other hand, more fishing time for me...