I have synced iCal on Snow Leopard with my iCloud iCal. So far, I have got all the calendars and events to show up on the 10.6 Mac, but I haven't yet tested syncing from the 10.6 machine to iCloud and on to my 10.7 Mac. I don't have an iOS device so I can't test that. On the 10.7 Mac I still have iSync. I kept it so that I can sync with an old mobile phone. With iCloud set up for iCal 5.0.1 on the 10.7 Mac, I opened iSync and looked at the calendars listed under the device (my old mobile phone). The list allows you to select which calendars you want to sync to the device, listing each one. In my case, each calendar entry on that list now takes the form: <Calendar Name>[<AppleID email address>@<iCloud CalDav server name>] My <iCloud CalDav server name> is <p06-caldav.icloud.com> but your mileage may vary for that one. (Omit the angle brackets when you're actually entering these things.) I made a note of the part in square brackets above and then switched to the 10.6 Mac, where I opened iCal 4.0.4. There I selected iCal>Preferences… and hit the Accounts tab. I clicked + to create a new account and selected CalDav as Account type. Then I entered the following: User name: <AppleID email address> Password: AppleID password Server address: <iCloud CalDav server name> Next I clicked create. The account loaded all my iCloud calendars into the sidebar in iCal 4.0.4, listed under the heading of my AppleID email address. I'm not sure how this could be done without iSync on the 10.7 machine, but I'm sure that a copy iSync can be found somewhere by those who really want it. I'll leave that up to you. ---------- I just tested push syncing from 10.6 to 10.7 and vice versa and both work fine. Can someone test this with an iOS device and let us know how they get on? Thanks. PS If you don't have iSync then it may be possible to get the server address from one of the info.plist files inside your Library>Calendars folder in Lion. (If you can't see that folder in Finder then select Go>Go To Folder… and then enter ~/Library/ and hit Go.) In that Library folder look in Calendars and then check the folder that ends .caldav - on my 10.7 Mac there's an info.plist file in there that mentions the correct server for me. I've written this up here: http://skangerland.blogspot.com/2011/10/how-to-get-ical-with-icloud-working-in.html I'll keep that updated with anything else I can figure out. Thanks.