Twitter: The Strength of Ephemeral Ties?

Whilst shaving this morning I was listening to the Oxford Internet Institute podcast Facebook: The Strength of Weak Ties, this got me thinking about the nature of Twitter ties. The title, The Strength of Weak Ties, comes from Granovetter's seminal paper of the same name, emphasising the importance of acquaintances as well of friends: close friends often have access to the same networks of people and information, whilst acquaintances have access to a different set of people and information. Although Twitter includes strong and weak ties, it also includes a new sort of relationship: the 'ephemeral' ties.

People are regularly contacted on Twitter by strangers in response to comments they have posted. If I mention that I am doing some programming in Python a stranger may ask what I am programming; if I say I am off to a conference, a stranger may point out that they are going to; if I ask a question, a stranger may answer.

Such connections are weaker than 'weak ties' as there is no permanence to the connection, they are transitory or 'ephemeral'. Whilst such connections are not new on the Internet, has any other technology emphasised the importance of ephemeral ties to such an extent as Twitter?