Since my last post on this topic a few things have changed. Some good, some not so much...
Let's get the bad news out of the way first.
The new iOS SDK is no longer free. That's right, XCode 4 now costs $5.00 on the AppStore. Oh, and it only runs on Snow Leopard. There seem to be a few places where you can get older versions of XCode for free, but Apple seems to be sweeping this into a corner. Oh well. I will say though that the new XCode is worth the five bucks. It has a lot of new features that make development much easier. So if you have Snow Leopard you should certainly drop the dough and get XCode 4.
On the upside we have two bits of very good news.
The first is that Apple is really pushing resources for folks to develop Apps for iOS. One example of this is that they have compiled a whole page of iTunes U and podcast resources for development, marketing and business management. There's some really good stuff here including full courses for iOS development from Stanford and UCDavis. It's worth your time.
And finally, this Fall Apple will be releasing iOS5. Check out this video on the new features to be introduced.