Just picked up Manning's iPhone in Action, 2nd edition PDF for only $12.49 using MobileOrchard's discount code "moborc2".
It's part of the MEAP (Manning Early Access Program); at this point it's far from complete, but it includes the full 1st edition PDF as well. Print date is expected to be June 2010. You can also get it with the print edition for around $20 total (with discount code) if you like printed books. I still prefer printed books for things like novels, but for tech books I think I switched entirely to PDF a couple years ago.
This Week in iPhone News - January 15/2010
Manning: iPhone in Action, Second Edition
