The Massachusetts Historical Society recently started twittering the short entries that John Quincy Adams penned in his journal during his time in Russia in the early 1800s. His short, one or two line entries lend themselves well to the "short update" style of the medium. These early entries recording his trip to Russia tend to include the current location of their ship (the Horace), an observation about the weather, and a notation of what he was reading at the time. For example, one of my favorites to date, "8/6/1809: Thick fog. Scanty Wind - On George’s Bank. Lat: 42-34. Read Massillon’s Carême Sermons 2 & 3. Ladies &c. Sick."
I think this is a wonderful way to connect with people who might never be interested in a former president's journals. It's also a smart way to marry Web 2.0 technology with traditional methods of historical research. And I'm sure it doesn't hurt that they have received a lot of publicity about the project & donations to help support it - certainly two things all museums can appreciate.
Cheers to the Mass. Historical Society for this exciting project!