NSURLConnection is actually pretty simple to use but here are some tips:

1. Use the asynchronous mode for any reasonably large file (bigger than a few KB) as people might be on a slow Edge network connection and locking up the view is never a good thing.
2. Do not send the message “start” to your connection if you use connectionWithRequest or initWithRequest to initialize your connection as you’ll get the nasty “EXC_BAD_ACCESS” error mentioned above. The reason for this is simple:  You’ve scheduled your connection to time out in n seconds, the method that initializes the connection starts fetching data immediately. You then send the message “start,” which spins off the connection trying to fetch data again. This works fine except that the original attempt eventually times out and tries to call back, hosing everything over and crashing your application hard core. Oops. You should only send the message “start” to your connection if you initialize it with initWithRequest:delegate:startImmediately.
3. When setting up NSURLRequest to pass to NSURLConnection, I highly recommend using NSMutableURLRequest so you can set the User-Agent header.  Some http servers may not return data, even for a simple GET without the User-Agent.  It’s my understanding that User-Agents are optional, but I do not know if said server behavior is nonstandard.

    NSMutableURLRequest *request  = [NSMutableURLRequest requestWithURL:[NSURL URLWithString: @"http://myurl.com"] cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:15.0];

    //Borrow FF2’s User-Agent

[request setValue: @"Mozilla/5.0 (Macintosh; U; Intel Mac OS X; en-US; rv:1.8.1.16) Gecko/20080702 Firefox/2.0.0.16" forHTTPHeaderField: @"User-Agent"];

I hope this saves someone some time.

If you don’t have these keys, remove your certificate from Keychain and remove your provisioning file (from ~/Library/MobileDevice/Provisioning Profile). Installing the same old certificates over and over will NOT help — you have to remove them all from your system and invalidate the certificate and distribution profile on the Apple Developer Connection page, then start the process over again.  When you generate the initial request and upload the certificate request to Apple’s site, check Keychain Access for the the public/private keys — if they’re there, you’re on the right track.

From there, clean your build and follow the instructions on Apple’s site and you’ll be good to go.  Make sure you close xcode prior to installing the provisioning profile again (I just copied mine to the directory instead of dragging it onto xcode or itunes).

Edit: Oh and heaven forbid people have applications that actually run in the background.  That would be the “wrong solution” so instead we’ll wait until september for them to give us a server to push “events” to the phones instead of letting us have the functionality immediately.  Everyone should just forget that practically every other mobile platform out there aside from the ever-crappy PalmOS allows background processes in some form or another without killing battery life.

Edit 2: So it looks like it was a sham (copied from the google maps terms), but the first edit still stands.