Augmentation extends, expands or adds to your abilities; computers, mobile phones and virtual worlds provide various forms of augmentation. Augmentationists use Second Life as a tool to expand their income, skill-set, social sphere, job network, whatever
The Immersionist viewpoint is pretty much always given as "that SL is its own thing and should not be contaminated by anything from the outside". There's just one problem with that.
That doesn't describe immersion. It's not even close. That's Escapism, essentially (or Separatism, if you prefer the word) but it isn't immersion.
Immersion is about attention (or getting wet, or astronomy - but those aren't really relevant definitions to the topic at hand). Immersion is fundamentally focused and concentrated attention. The sort that is vital to Escapists, and to Augmentationists, if either are to derive benefits from a virtual world.
Let's a priori assume for the moment that Escapism and Augmentationism are two ends of spectrum. Immediately, Bennetsen's observations make sense. The confusion with the word immersion is what's clouded the essential debate thus far, as many commentators on the topic have wandered between the provided definition and the pre-existing definition.
While Escapism and Augmentationism are distinct philosophical positions (things you choose), immersion ultimately is a mental and circumstantial quality that is equally applicable to either (something you have, independent of both positions).
In a sense, this is a debate that never was, with immersion getting falsely caught up in a struggle between polar positions, where it had no place as an option. Problem is, unless everyone's using the key terms in compatible ways, no useful discussion is taking place.
Augmentation vs Escapism -- now that's an interesting sociological tension!