Here's what we're working on and what's coming next for Cirrux. We build in public and ship regularly.
A dedicated Cirrux calendar client, built on the CalDAV foundations already powering Mail and Drive. The first version is launching in the next couple of weeks.
Writing in the workspace: drafts, notes and documents that live next to your mail and files. Probably the most requested feature after Calendar, planned for the summer.
Ongoing sync from Microsoft Outlook to Cirrux, the biggest remaining migration path after Google and IMAP. The foundation is already underway, and the IMAP, vCard and iCal importers make a one-time migration possible today.