Kitchen Reno - Wall to Wall

Always busy around here - in addition to this kitchen renovation, our summer is full of trips to the pool, dances in the sprinkler, a bit of veggie gardening, and playing with friends.  Updates have been sporadic, but we ARE making progress!
This weekend was all about a little more wiring and a little more drywall.  It's not all up, but the room has about 90% of the studs covered!  It's starting to look and feel like a real room.  Let's take a look!

 OK so what you may notice is that this isn't ALL drywall!  Yeah, what's that all about?  Cabinet support.  For areas of the wall that will be holding up a wall cabinet, we decided to go with 1/2 " plywood instead of drywall.  Screws will hold well in there (in case we can't hit a stud) and because the "studs" on the exterior walls are ripped down 2x4s the plywood will add stability and strength.  It's a good thing.
What if you SEE it!??!?  You won't.  Our plan is to tile the back splash from the counter to the cabinets so even if a smidge of plywood is visible under the cabinet (and Jason assures me that it won't be visible), it would be covered with some pretty tile later.  
Also, note those little white wires poking out between the drywall & the plywood?  Those are the wires for the under cabinet lighting and will be connected to the light switch on the other side of the room.
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Question for readers - what's the longest DIY project you guys have ever undertaken?