Yes, it does support WIDI.  However, getting it hooked up the first time was not easy for me.  I just got a 15z with an i7 processor and a touch screen.  I had read magazine reviews of the computer indicating it would support WIDI.  However, the WIDI software was not installed on the computer when I got it.  The computer rejected installation attempts from files I downloaded both from Intel and the Dell support page.  Last night I spent 2+ hours on the phone with a persistent technician who after an extended remote assistance software session eventually got it to install and work.   I have been very happy with the computer.  It took a lot longer with tech support than I would like, but they did get WIDI working.  At this writing this is a new computer model with a relatively new operating system.  I will bet as the months in 2013 pass by, they improve the WIDI support offered out of the box or with software updates.
Does the 15z 5523 support WIDI (wireless display)? I'm thinking if purchasing the Netgear PTV3000 but I'm confused about whether this will work or not. I'm already planning on replacing the wireless card with an Intel Centrino 6235. Not sure if this makes a difference or not. My understanding at this point is that I need an Intel processor I3, I5 or i7 and a compatible wireless card and some software from Intel to support everything.
Inspiron 15z 5523 and WIDI