In particular, migrating calendar entries from Outlook was near impossible.
- OL2003 lets one export one single calendar item to iCal format (and you have to use a trick to even get there).
- OL2007 lets you export more than one entry at once, if the entries are less than 1000 and do not span more than a 10 year periode (earliest to latest entry).
Cut a long story short, I wrote a little program, available on SourceForge that exports all calendar items at once, regardlessly.
FreeMiCal comes as a source zip-package or just the executables (for easy use). It is written in C# and requires nothing more than a Windows machine with Outlook 2003/2007 and .NET 2.0 installed.
FreeMiCal was downloaded over 11.000 times in the last year. It seems to do the job and helps obliviate Outlooks calendar lock-in.