I have more than 1 Mac, and I would like to do development on all of them. I know I need to sync my phone on each machine, but that is the least of my problems. It looks like I am not able to run apps on my phone except apps that are developed on one of them.
Is there anyway (sensible) to be able to use both my MacPro and MacBook Pro ?
I use a MacPro and a MacBook Pro for development with no problems. Make sure you have the same certificates, mobileprovisions, and (obviously) code on both machines. I find it useful to use Keychain syncing via MobileMe.
have you installed the certificated needed from all machines, maybe you forgot to add the certificate from one.
You can copy your signing certificates from one machine to another (via Keychain).
You do not need to sync your iPhone to both machines; XCode can install and extract your app on any phone, not only the ones that sync to that machine.
As the others have already said make sure you have the same sure you have the same certificates and things on both machines.
Recently I stumbled across a great way of making sure you have the same code on both machines, use DropBox. Its free for the first 2GB and will keep your source code on both machines exactly the same, meaning no having to remember to copy work around. Its super simple and in my experience just works.