Speaking of Cocoa (and iPhone) programming, for a change.
Having trouble with spurious EXC_BAD_ACCESS crashes when using NSURLConnection? NSZombie giving you not very clear messages about [Not A Type retain], pointing to an address that malloc_history says has been allocated somewhere with only framework code in the call stack? See Amro Mousa's blog entry about the subject.
In a nutshell, don't send the start message to a NSURLConnection object you've initialized with a +connectionWithRequest:delegate: or -initWithRequest:delegate:. It'll break stuff.
Apple, how about a warning about this in the docs? The docs for -start say "Causes the receiver to begin loading data, if it has not already.", not "Will break your program and make you waste uncounted hours debugging if receiver has already started." Or how about preventing this in the code? Is there some scenario where you'd want to call start after the object has already started?