Solution: You have to go back to the target, and then toggle the Code Signing Identity->Any iPhone OS Device to iPhone Developer.

This might be because I had XCode running while doing the installation of the GM Seed and had to use the ‘kill’terminal command.

Firstly, you will need to enroll into the iPhone dev. This will require an Apple ID. 

From my experience it was easier to enroll as a single developer than rather as a company/business (as it required less documentation) and the turnaround time was 1-2 days (this included acceptance of payment for developing).

Please checkout: http://developer.apple.com/iphone  for further information

Follow the instructions as per the website above. 

Generally, the process is the following:

1. Download SDK, OS Firmware and iTunes images (these should be in format *.dmg)
2. Install the software as usual (the OS Beta Firmware is a little different – read next point)
3. When installing a beta version of the iPhone OS (eg. iPhone 3.0 Beta 5) in iTunes you have to hold the ‘Option’key and then left mouse click on ‘Restore’. The restore button is located under ‘Devices’->your iPhone name->Summary->Version section. I found this counter intuitive and not well documented. This will open a dialog box for you to select your iPhone OS Firmware. Navigate and select the beta OS. Remember this will wipe out all the Apps on the iPhone but will not actually wipe anything else off (as long as you did a backup).
4. Click on the ‘iPhone Developer Program Portal’ on the right hand pane.  (This took me forever to find!)
5. Follow the process of creating a team name, developer certificate, App ID and Provision certificates. Note the  developer certificate and provision certificate are most important and have to be installed on both the KeyChain and in XCode Organizer, respectively. 
6. In XCode, for the respective applications, make sure the Target information is correct. That is:

• Base SDK = iPhone Device 3.0
• Code Signing Identity=iPhone <name> (this is the developer certificate name on the Key Chain).
• Identifier=com.domainname.AppName

When running XCode I had a simple ‘hello world’app that . However, I ran into a few issues. 

Error: XCode would not build the app as the Identifier: com.domain.AppName was incorrect or could not be recognised.

Fix: The fix was the Provisioning certificate was only dragged into the Provisioning section of the Devices->iPhone Name in XCode Organizer. However, this was NOT the only place to put the provisioning certificate, you also had to drag’n'drop it into IPHONE DEVELOPMENT->Provisioning Profiles as well!

Error:  XCode and A signed resource has been added, modified, or deleted.

Fix: “*If you do not have the WWDR intermediate certificate installed, click here to download now.”

The above link basically downloads the following: AppleWWDRCA.cer (Apple World Wide Relations Certificate Authority). This means that you need two certificates installed on your Mac OS X keychain in order to build the application.  Therefore, your keychain should have the following 2 certificates:

• iPhone Developer: <name> (this is the one you were told to generate and download via the iPhone portal)
• Apple Worldwide Developer Relations Certification Authority 

Issue: XCode cannot find the software image to install this version. 

This error can be seen when navigating to the IPHONE DEVELOPMENT->Software Images section as there is no 3.0 Beta version. This does not stop the app to be installed and run, but the ‘Console’reports of ‘Unknown Kernel [0]‘ messages. 

Fix: Unknown.   The iPhone firmware images are placed at /Users/<username>/Library/iTunes/iPhone Software Updates. Note the firmware has an extension of: *.ipsw. Therefore, open the file iPhone OS 3.0 Beta .dmg and then copy the .ipsw file into the directory mentioned. This DOES NOT remove the message ‘Unknown Kernel [0]‘ but it appears to be just a notice message <Debug> and is not an actual error.