If you are creating applications for the iPhone, you know what an absolute pain in the butt it is to set up your device and all of the associated certificates and profiles so that you can use your iPhone for development... anytime you need to go through a 50 page document to set something up, you know it's going to be trouble.

If you're trying to create a second iPhone application, you may be tempted to just start the process all over again. It won't take you long to find out you are stuffed. When you go to create a new certificate, either for development or distribution, you'll find that the "Add Certificate" button is disabled.

Don't panic. And don't call tech support at Apple (they told me to revoke my current certificate, which completely hosed me). The thing to know, which of course they never bother to explain, is that you only need one certificate. You can reuse it to create multiple App IDs and provisioning profiles. So if you're setting up for a second application, just skip straight to the page for "Creating your App ID" and follow the instructions from there.

Once you go through the process of creating the App ID and the provisioning profile for the new application, when you go back to the certificates page you'll see that your new app is listed under the current certificate.