I was thumbing through the Canadian section and thought to respond to this thread, albeit belatedly.
The biggest problem one faces with any sort of salvage is how to conserve what was recovered. Wood, leather, iron, even ceramics will deteriorate when brought to the surface and dried out. It's arguably worse than letting the stuff rot in place. Salvage also destroys the archaeological context of the artifact.
One of the ways we are preventing damage to historic wooden wrecks in the Chicago area is to sink steel ships as dive attractions. The Straits of Mackinaw, an old car ferry, was sunk off Chicago five years ago. It has been hugely popular and relieved much of the pressure from more delicate wooden wrecks.
We are also cleaning up a 100 ft. party boat, currently named the Buccaneer, as a dive attraction. For Canadians this boat has some historic significance. It was built as a U.S. Coast Guard revenue cutter to enforce Prohibition during the 1920's and 30's. As the USCGRC Dexter it distinguished itself by sinking a Canadian flagged sloop named "I'm Alone" in international waters (oopsie) precipitating an international incident (or shall we say "act of war"?). It did redeem itself with service during WW II and ended its days as a booze barge.