The following are iPhone development blogs I often read. Note I used Google reader to get them. I also listed some of the blogs under “dev” category in the side bar (small).
Technical
iPhone development by Jeff Lamarche. Jeff is the author of the best beginners book for iPhone dev “Beginning iPhone development”. Recently I found his profile at LinkedIn, and found he was a law school graduate, which is total surprise to me. He is definitely not a lawyer type in terms of writing (blog) and talking style (from his tweets).
Cocoanetics (aka Dr. Touch): Oliver Drobnik, the former Windows Admin turned full time iPhone iOS developer lives in Austria (Europe). Note he recently changed the name from Dr. Touch to Cocoanetics. Regardless the name change, I found he has a very good sense of both technology and business: I think his article on Notifications and “Part Store” (he sold his components software like parts) are very interesting.
iPhone developer:tips written primarily by John Muchow, who is the author of Core J2ME (which is the primary mobile development language pre iPhone, it is still used on Blackberry platform, and note Android used a different Java virtual machine developed by Google). I think some article such as “rename Xcode project”, “Prevent application being placed in background” etc. to be interesting.
iPhone development blog: written by Nick Dalton who got into iPhone dev early. A lot of goodies include this iPhone iOS app store reject reasons. I believe he is a co-founder and CTO of a mobile development firm in SF (can not recall the company name on top of my head, you may google).
Ray Wenderlich: the blog bears the author’s name. It has a lot of meaningful tutorials (not those “Hello world” stuff). Besides that, I found this How to host beta test for iOS app” to be interesting.
Other Resources, news, gossips etc
iPhone developer news (Apple): get it from Apple iOS developer center. The official place for all the announcement etc.
Mobile Orchard: used to be good technical stuff, stopped update this April, just resumed blogging.
43 iPhone app development resources: the list is a bit dated, but still useful.
I will add more as time goes.