This page talks about recent events in the project and where it's heading.

After a long break, I decided it was time to move this project forward a bit. With today's release, the Cell.Format property is finally in place. It seems to work. With each cell now having awareness of its format, I was also able to implement conversion of dates and times from Excel's quasi-formats to standard ISO format. There are many variations of number formats that are not yet supported, but it will be easy to add support for these later (in Workbook.LoadStyles()).