Importing Gmail Contacts into an iPhone 3G

Thank you in advance to anyone who can offer any advice to my question. I apologize if this is a newbie-type question, but I've searched around and haven't found a great solution yet. Here is my dilemma:

I just purchased an iPhone 3G this weekend. Everything is working fine so far; I set up my Gmail acct on it with no problems. But is there a way to import my Gmail contacts into my iPhone? I've connected my iPhone to my Mac and have searched for an option for this in iTunes, but the only thing I see is an option to import items from a Yahoo account.

I did find this app: www.syncinablink.com, but I wanted to see if there was any other alternative before I tried it out.

I have 100 contacts that I've already manually added into my Iphone (from my old cell phone), but I would like to merge my Iphone contacts and my Gmail contacts, and then have both of those places update each other automatically so that when I make a change to an iPhone contact, the change is automatically made in my Gmail contacts (and vice versa). Is that possible?

Thank you in advance for any/all help.