I have a new iPhone 4S, a MacBook Pro and a MacBook both with Snow Leopard (10.6.8). I had no problem syncing my Google email accounts with my phone and do not need iCloud for that. But I had a lot of problems trying to sync my Contacts and Calendars. After much experimenting and hours on the phone with a senior Apple tech support guy, I was able to sync my two Calendars (work & home). I have only partially solved the Contacts syncing issue.
First, contrary to what people are hearing, iCloud actually does work with Snow Leopard, at least partially. You can create an iCloud account via your iPhone or iPad and iTunes will recognize that you are syncing calendars and contacts via iCloud. In fact, it warns you that if you also sync via USB cable, you are likely to encounter some duplicates. And that is accurate.
Second, I could not get calendar syncing to work between iCal and iCloud. iCal in 10.6.8 just does not seem to have the ability to do it. It gets complicated since I think it is trying to use iSync to make it happen. It's very messy to setup and I finally gave up. However, I was able to get my calendars to sync by using BusyCal <http://www.busymac.com/index.html>. It uses iCal's database, is a much better calendar, and has the capability to easily sync each of my calendars with iCloud. It is not free.
Third, I can get my Contacts to sync between my laptop, iPhone and iCloud... sort of. Based on the Apple tech guy's suggestions, I am syncing my iPhone with iCloud wirelessly and my Address Book on my laptop via USB cable through iTunes. The Apple Tech guy said this approach "should" work. He said the master list of contacts would now be stored on iCloud and "should" be syncing with my laptop and iPhone. And it does, almost. My contacts are is mostly in sync. It's not perfect... yet. I'm still working on it.