Sena's recently-released Executive Sleeve for iPad 2 ($100) is pretty much what we've come to expect from a high-end leather envelope: it has enough room for the iPad 2 to slide right in, with or without Apple's Smart Cover attached. Embedded magnets in the flap and body hold the case shut; unlike several other models we've seen in recent months, the magnets don't show through the leather, which looks and feels particularly nice. Four different colors…