I bought the KDL-40SL130 at Costco last night (Happy Birthday to me!) and it is 720P. Display resolution from the spec chart on pg. 44 of the book is 1,366x768.
That being said, it had the best picture of any TV on their floor. My girlfriend and I didn't even think twice. We each grabbed a handle and out the door. Plus, there's a $200 off coupon in the blue length-wise coupon book.
Haven't had time to really dig into it yet, but that will happen soon. Going...