Clients frequently request that I run my calendar on their calendaring systems so that they can schedule me for meetings. I can't really do this because I work for a number of clients and I use my calendar to manage my non-client work and my personal activities. I have a hard enough time managing my time. I don't need the additional burden of replicating the same information in multiple closed systems.
My new work-around is using Spanning Sync (SS) to synchronize my local iCal calendar with a Google Calendar that shows busy times to the general public. So far the solution looks promising but there are some compromises that I have had to make. The biggest one is that I like to have personal and work on different calendars within iCal. SS only does a one-to-one mapping between iCal and Google Calendars so I had to merge my local calendars into one to get a single, public free/busy Google calendar. I recently noticed that iCal allows you to create "groups" of calendars and I was hoping that SS would synchronize a group of calendars as one calendar. Of course, since SS does bi-directional synchronization, this wouldn't really work (how would SS know which iCal calendar to put an event that came from Google Calendar?).
The other compromise is that I had to make my calendar open to the world. I would have preferred to only share it with people I choose. It seems that I can only share with other registered Google users (which is probably everyone but on principle I don't like to force people to register for anything). The public URL is relatively long and obscure but I am sure it is guessable. This is not a huge issue because I am only sharing when I have meetings not what I am doing.
I am wondering what other people are doing when faced with similar requirements.