I wouldn't anticipate any significant iPhone or iPod hardware update, that's usually reserved for later in the year. The safe bet would be to expect updates to the MacBook Pro, Air and Mac Pro lines. With the Mac Mini as an added bonus. It is a developers conference after all.
Personally, I am waiting for a MacBook Pro update. My current everyday MacBook Pro I use for everything and take everywhere has just passed 3 years of service, late-2010 model. Not one thing wrong, not one fault. Battery also scooted past 500 cycles and is doing alright, not 7 hours but its reasonable.
My perfect MacBook: Air unibody, Pro graphics and internals, Retina display, 13".