[kndyry]

Playing devil's advocate, my first response would be to register accounts for, say, the 2,500 most common English words and then compose some rather nice essays.

@Yes, @something @like @that @might @prove @quite @funny.

[devindotcom]

Perhaps make it only the 1000 most common words and rename Twitter "Thing Sayer"?

[cyrus_]

Length of mentions could be capped at 140 to prevent this hack.