Then you can go on with the steps for setting up Google Sync.
The problem is that this new service doesn't yet give that much value (at least to me). As I described on a previous post, there is already a 3rd-party provider (Nueva Sync) that allows you to sync Google calendar. The only "advantage" is maybe that you don't have to rely on 3rd party providers. When I read about the new sync service first, I expected to have some additional service on my iPhone s.t. I can re-use the MS Exchange account on it for other purposes because that's the major problem. If for instance I'd like to keep my work mails synched over MS exchange, it is not possible since the only available exchange account on the iPhone is already occupied with the sync service. So that's a bit awkward.
Important note: When you set up the synchronization of calendars Google will initially just synchronize your main calendar. I had to search around the web for a while to find the place where you can customize these synchronization options: Google Mobile Help.
You basically have to go to http://m.google.com/sync. If you get a message that your device is not supported, try to change the language settings to English (US) by clicking the language link on the page you see. The italian version didn't work on my iPhone. You should then see the following
Another app that has been ported (as web-app) to the iPhone is Google Tasks. It was already available as a Gmail Labs app for a longer time. Now it's becoming however really interesting when you have the possibility to also to use it on your mobile. Just navigate on your iPhone to http://mail.google.com/tasks/iphone and then you can add it to your iPhone home screen.
And you can follow the sync process in real time. Changing a task description on your phone will just last about seconds and you'll see it changing on your iGoogle task gadget. The only problem with the app (as with most Google's apps) is that they just work when you have an internet connection since they're web-based. Porting Gears to the iPhone would give an enourmous benefit here.