If you have a mix of Macs on Lion and Snow Leopard and/or iDevices, things get a bit more complicated.
If you happen to have a MobileMe account, you can keep using it for now, but MobileMe will go dark on June 20, 2012. Eventually you will have to come up with another solution.
I'm sure that somebody is working feverishly to create a third-party solution for iCloud on Snow Leopard. I'll let you know as soon as I hear of anything.
If you don't want to wait, you can use a Yahoo! Mail account for syncing all of your Lion and Show Leopard Macs and your iDevices:
First, create an email account at mail.yahoo.com if you don't already have one. Setup on Lion:
- Open System Preferences under the Apple Menu in the Menu Bar.
- Go to the Mail, Contacts and Calendars preference pane.
- Click the + button on the bottom left and select Yahoo!
- Enter your Yahoo! Mail credentials.
- Make sure that Email, Contacts and Calendars are all checked.
- Go to Settings.
- Go to Mail, Contacts, Calendars.
- Add a new Yahoo! account.
- Make sure Mail, Contacts and Calendars are turned on.
- Go to Mail.app preferences and add a Yahoo! email account.
- Go to Address Book preferences and set up Synchronize with Yahoo
- Go to iCal and ....