Work TJ's RRULE and other date parsing code into the main parsing code
Implement serialization for iCalendar (i.e., ignore vCard QP stuff for now), particularly RRULE because dateutil.rrule will parse RRULEs but it won't serialize them
Write more validation classes for iCalendar
Calsify
Send an email to the Calsify list with ideas about creating automated test suites for iCalendar formatted documents
Long term
Vobject
Deal smoothly with QP data from vCard 2.1
Do more thorough testing/validation
Chandler
Implement iCalendar import/export for Chandler using vobject