Here is how I solved this problem (e.g., the problem of being unable to edit calendar events in the new 2.0 iPod/iPhone software). First of all, my calendar, email, and contacts are stored on a Microsoft Exchange 2003 server. Second I was able to sync wirelessly over WIFI.
I tried changing my user name on my iPod Touch from "user" to "UseR" (in other words, I called my CIS support and got the exact capitalization of my user name). I changed username spelling in the preferences on my iPod Touch with the 2.0 software. But I still had the same problem: all calendar entries were invitations and could not be edited. So I took a deep breath and
deleted the account off my iPod Touch. Then I started afresh with the new, correctly capitalized username and all other account info. After the device resynced, VOILA! it was fixed. I am now able to edit all calendar events, and there are no more silly invitations. I hope this helps someone out there!