I don't have any inside knowledge w/ Josh / Nilay's exit, but I can say Enagdget editors tend to last about three years. Peter "left" and worked on rcrdlbl right after AOL acquired Engadget (twoish years into the site's life), then Ryan left after three years of tenure (2008), now Josh is leaving... not a surprise.

Blogging the Engadget way is hard. You have to always be on your game, making sure posts are timed, etc. It's not a picnic. These guys are really good at what they do, and having a corporate overlord wears on you.

[Disclosure: I was at Engadget in 2005-2007]