Is it possible to sync iCal with iCloud on Lion machines but still subscribe on pre-Lion machines?

Question

I absolutely love iCal, and have a very complicated system set up such that various individuals/computers can access my calendars.  I was thrilled about iCloud, as that mean that I would not have to worry about remembering events until I found myself in front of the "main" machine, but could update iCal from all Lion/iOS5 devices, which are my general working machines.
But, it appears that iCloud has removed my former webcal publishing, and now my pre-Lion machines cannot keep up to date with the calendars.  So, I've done a bunch of investigating, and think I have found a work-around, but I still have a concern about it, and am also wondering if there is a better solution.
So, what I want to do is this:
I have two Macs running Lion (laptop, desktop) and an iPhone running iOS5 that I would like to be able to update calendars from and have it show up on all.  iCloud neatly accomplishes this (whereas before, I had to wait to find myself in front of the desktop, or remember to sync the iPhone).
I also have a plethora of older Macs, owned by myself, people in my group, and my family, that currently subscribe to various webcal addresses to keep up with "Work" and "Home" calendars, on a read-only basis.  The Macs are running anywhere from OS 10.2 to 10.6.  Upgrading to Lion is *not* an option -- first of all, they're not all my machines, and second of all, some are truly old (10.2 is running on a G3 -- yes, a G3, still in working order and completely fit for its purpose, with no plans to update until the machine physically stops working, but 10.2 is the most recent OS it can run).
The work-around I found is this:
I set the iCloud calendars to share with "everyone" which provides me with a webcal address that I can send to people and tell them to subscribe to it in their iCals.
My concern is:
I am concerned about the "everyone" sharing:  I previously used a prviate, password-protected third party webcal pubishing service.  The URLs the everyone-sharing produces look complicated enough that it is unlikely that anyone would "guess" it, but is possible to browse public iCalendars somewhere?  The information in the calendars isn't hugely sensitive, but some of it is private enough it would cause a stink if some people blundered across the "Work" calendar, and perhaps some embarrassment if others found the "Home" calendar (especially as work people will know I am using this method).  Does anyone know how easy it is to access these calendars if you have not been provided the URL by the publisher?
And finally, is there  a better solution?  Ideally, I'd have password-protected webcal sharing.  It looked to me that the "only with people you invite" choice requires people to both have an iCloud account, and then use an iCloud enabled OS in order to get it into their iCal, which won't work with the pre-lion machines.  But perhaps I am wrong about this?

Answer 1

Sharing (not publishing) can be done privately - which requires the recipients to have an iCloud account - or publicly. As you say, this means than anyone who knows the URL can subscribe: but there's no published list of calendars, people who don't know the URL would have to guess it so the chances of them finding it are fairly low.