While I used for several months the service offered by ScheduleWorld, I didn't like the idea that my calendar was stored elsewhere than on one of my machines. The fact that ScheduleWorld decided recently to switch to V2 (and now don't provide the service for free anymore), it pushed me to find a solution to sync my calendar between my Nokia E51 and my Linux laptop/computers. I really appreciate my Nokia mobile phone, but unfortunately it doesn't support iCal (and I've not found a symbian app that could do that ..) . The only protocols that the Nokia can 'talk' is SyncML or 'ActiveSync' (through their 'Mail for Exchange' free plugin) . That directly limits the scope for the backend. While I considered Funambol at a time (to use SyncML) , I finally ended with Zarafa (and Z-push) . It's all open-source (in the community edition though) and emulates an ical (and caldav support is now available in the 6.30 release) and Z-push emulates an 'ActiveSync-over-the-air' server so I'm now able to directly sync my calendar/contacts/tasks/mails from my Nokia mobile phone to the server (using a MySQL backend) and either use the Zarafa webaccess (that I don't use that much though) or Thunderbird with the Lightning extension . (every "iCal aware" program works of course)
Note : Z-push isn't yet available in the RPM format on the Zarafa website due to a clause in the GPL license (more informations on the RPMfusion bugzilla related page) . Thanks to Robert Scheck a spec file was written but isn't yet available. Robert is interested in seeing his package landing in EPEL and RPMfusion while I consider myself providing it in RPMforge. In the meantime, if you're interested in the RPM version, feel free to 'poke' me or consult the spec file in the RPMfusion bugzilla .