Amazing how an app can tip so quickly. Maybe its the connectors that let you post to multiple networks, so you only need to write once. Regardless, once Twitter recast itself as a microblogging service (vs. a party/barhopping planning tool) its become the defacto communication standard. I figure it will last about 6 months, since the noise has quickly become deafening.
Facebook is already there. All the extra features that put additional information into the feed have crowded out the really interesting stuff – what friends and acquaintances are really doing and thinking about.
I remain convinced, however, that opt-in peer to peer communication will supplant email as the main communication medium within a couple years. This means the cheapest marketing medium will continue to implode, and marketers will need to keep innovating to stay up with their customers.