Mike Ash with a great recap of some techniques you will probably be familiar with for defining constants in C/Obj-C along with a technique you might not be so familiar with for cutting down on the ugly by using structs to namespace constants.
A new open source networking library by Gowalla. I was hooked as soon as I read "If you're tired of massive libraries that try to do too much..." and sure enough this looks really good so far.
Of course, there are other ways to uniquely identify an iOS device rather than using the UDID.
Ryan Dillon on creating a circular scrolling control. If you haven't done much with drawing using Core Animation layers then this is a great introductory article to dig into.
More Core Animation goodness! Bob McCune with a repo full of a great set of CA demos from a Minnesota CocoaHeads meeting earlier this year.