This week, Microsoft published an open source (Apache 2) SDK to read PST files. From what I heard, it works with Unicode PST files as generated by Outlook 2003 or later.
It’s a healthy move on Microsoft’s part, as it releases their users from feeling like their data is locked in to their relationship with Outlook. I hope the code is easy to use, etc.
I’d naturally be very interested to hear of anyone experimenting with using this code in an add-on to make the process of importing all one’s data from Outlook into Thunderbird. If you know of such an effort, let me know!