While migrating to Kontact it might come up that a large set of ics files have to be imported into Kontact. There is a GUI way to do that, but that involves a large number of clicks for each file. Easier is the command line way:
$ ls *.ics | xargs -n 1 konsolekalendar --file ~/.kde/share/apps/korganizer/std.ics --import
Another way is to copy all ics files to a directory. A new calendar can be created with this new directory which afterwards contains all the data from the ics files. This calendar can again be exported as one single ics files which can be easily imported everywhere.
/home/liquidat 
How about simply drag & dropping the files from Dolphin to Kontact? that would be the ideal way, IMO.
Janne: lol 🙂
My vote would go to such implementation as well!
Janne, your idea does not really work for some thousand ics files, and that was what I had in mind. 🙂
Sure, there might be “issues” with truly huge numbers, but even then you could just do a “select all”, and drag away. Or maybe there could be a tool in Kontact where you could point it to a directory and tell it to import all relevant files it finds in that directory?
Janne, that could also be possible, why not. If you prefer to work with a GUI – or need to work with it – that might be the ideal way.
In case you have to manage a desktop remotely, or need to script the import for 100 clients GUIs are not an option at all.