Joshua Topolsky has been at Engadget for four years and tonight he has written the sad announcement of his departure. His reasons? Nothing more than: "There are things I'm after and challenges I want to take on that just don't fit with my day-to-day schedule here, so off I go." He will remain at Engadget as an editor-at-large, but will be working on various projects that he says we'll "be hearing about soon." Read the full story.