Hi Guys,
I have the same issue with my corporate sync calendar entries for one of my work calendars - missing edit button, but I have found a valid workaround which works well for me. BTW, I am using a Motorola Defy On Android 2.1, Rooted.
If I create a calendar entry on my phone, I can edit it on both the phone and in Outlook, no problems (date, time, subject, contect, etc). But if it's created in Outlook on the PC (similar to being created in Google Calendar, etc) and sync'd to the phone, I cannot access an edit button and I cannot update the entry from the phone and I have to go to the PC to do so - not always convenient! Now this is isolated to just one of my corporate sync accounts, and I do not see this problem in the others I have (google and another corp sync account).
My workaround is to have a 3rd party calendar tool loaded on the phone to enable me to edit the entry if required when the standard droid app doesn't allow it. The app that works for me is free and is called "Touch Calendar Free" and I found it on the Android Marketplace, but try some others you come across if you like. When I come across an entry in my calendar which doesn't allow me to edit it (no edit button), I fire up Touch Calendar and edit it from there - works just fine and sync back to the Outlook calendar no problems.
It's only a work-around, not a fix, but it allows me to change an appointment on the phone that I would have otherwise would have had to go to the PC to change.
Let me know if it works for you guys!
Cheers.