To echo the others, immediately it means very little. Its a curiosity at first, and an interesting side note amongst gentlemen scientists. Benjamin Franklin will be lionized a little bit more in the pantheon of American heroes, and a few more things are posthumously named in his honor.
Now it will get interesting when the industrial and scientific means to create a practical telegraph are invented. If a practical telegraph complete with electromagnet is invented and introduced 20 years earlier, I think the results would be quite far ranging. It would certainly hasten the speed of colonization from the American west to the steppes of central Asia. It would also make the uprisings of 1848 more interesting depending on which side capitalizes upon the communication technology first.
The demand for copper, and copper wiring could cause some fairly major changes as well. Britain and to a lesser extent the united states, and belgium will likely be the nations to dominate the early telegraph industry (as well as the mass production of copper wiring) The upper peninsula is likely to experience a copper rush, boosting its population to a level that would make annexation by Michigan unlikely. Similer booms will likely occur the world over, as telegraph networks are built and subsidized by the various powers.