Unlike last year, when Apple only had ~1,200 distribution channels through Apple stores and Best Buys, this year it will have over 10,000 channels through Target, Walmart, AT&T, and Verizon. As a result of this diversity, Munster believes lines will be small.
(Although, he hedges a bit saying that Apple is selling the iPad starting at 5 pm on Friday, so it could have long lines.)
Short lines or not, Munster is still calling for iPad 2 to sell more quickly than iPad 1. He thinks Apple sells over 1 million iPad 2s in less than 28 days.