Mt. Pisgah Woods in Berlin
10/21/08

This growth on a Black Birch looked like a Chaga but at closer inspection turned out to be something else.
Guillaume Ayotte Cote says that is most likely Inonotus glomeratus
Bill Neill was not familiar with this conch but pointed to the true fruiting body of Inonotus glomeratus which he is familiar with.
http://mykoweb.prf.jcu.cz/polypores/list_iton.html
So it appears that Inonotus glomeratus has this additional similarity to Inonotus obliquus
Bill Neill also sent this link
http://maple.dnr.cornell.edu/insects-disease/InonotusGlomeratus.html
The thing is this one is growing on a birch rather than a maple, but mushrooms tend to choose different hosts in different parts of the world.
 

Side view.

Here is the information on the above link:

Formerly Polyporus glomeratus, this fungus causes a relatively common canker rot on sugar maple. It reportedly is the most important decay fungus of sugar maple in Ontario, accounting for up to 40 percent of volume losses. It also is found on red maple and beech.  Branch stubs and wounds are the primary entry points for infection. Once the decay is advanced in the stem, the fungus produces a sterile, thick mass of tissue that spreads over the wound area or around the branch stub. This soon turns black, crusty, and cracked. The canker is irregularly shaped and generally becomes elongate with raised margins. Canker rots produce fertile fruiting bodies or conks only after the tree dies. Canker rots cannot be eliminated from the forest, but maintaining healthy and wound-free trees and removing infected ones should reduce the incidence of these diseases.

Grafton MA
5/26/09

Side view of canker on Black Birch.

Front view.  About 8" wide.

Broke of about an inch cube to see what it looks on the inside.

On American Beech by Gould Meadow
West Stockbridge MA
5/3/09

A closer look.