Just in case anyone want to know how I do my viewing sessions....
90% of them are done in our office. We do have clients that have traveled 3+ hours to us, and those we do online using Zenfolio galleries.
For our normal sales session, they come in and have a seat in front of our 48" HDTV I use an apple TV to stream a slideshow ( animoto.com ) wirelessly from my PC in the office area. Even though I have a PC, I can use iTunes to stream the slideshow. As soon as the slideshow is finished, I hand them my iPad which has their images in a nice app called Portfolio for iPad. I have found my customers love being able to hold the iPad in their hand to go back and forth at their own will and look at them on their own pace.
The Portfolio app is also great because it has a function where you can make notes that are tied to each image (ie. 16x24 gallery wrap or convert to b/w, etc.)