I find the worst interrupters are not co-workers but impatient, micromanaging managers. Yup, the Dilbertian PHB's -- there just are too many of them out in the wild.
Coworkers can be a menace too. Two jobs before, I worked in a place where each team of ~8 people had their own room. On the floor, we had a bunch of "roamers" who would visit every room at random times to socialize. And then, within the team, we had the problem of everyone doing their own "break for cat memes" at a different time, and wanting to share the funny thing they saw immediately; we sort-of solved that by creating a dedicated IM chatroom for sharing off-topic posts, but then those would sometimes spill over into meatspace anyway, and suddenly you had half of the room discussing some stupid video while the other half tried to work. It was manageable at this level, though. An equilibrium.
(I have to admit that I did my own share of distracting my coworkers there; nobody was blameless in our room.)
