Up until now, there’s been an element of utopianism to Twitter—a communal sensibility, a sense of egalitariansim, a conviction of the value of conversation. A “social warmth,” Steven Johnson calls it in Time magazine’s current, Twitterphilic cover story.

Up until now, Twitter has been a space largely free of commercial concerns, a place where people could talk and share and explore without mercenary influences seeping into the interaction.

Up until now.