I've actually purchased a hosted microsoft exchange account that I use to sync my iphone to the exchange server. It's just like having outlook at work, but at home and on my iphone. Only 10 bucks a month. I've got a GTD solution for outlook, so it works great for me.
I use Pocket Informant for Iphone. It syncs wirelessly to Outlook now. Sync program is 'in public beta' at present (and free) and I've been using it two months. PI for iPhone is pretty close to GTD methodology with a few extra bits you can use or ignore.
I've recently given up Outlook and gone to other services that link seamlessly between iPhone, iPad, and PC. It was mentally stressful at first (I've been on Outlook for at least 10 years), but I really like not being tied to it.