Here's the solution to having the Fascinate calendar sync with Google Calendar. I've seen numerous people with the same problem and had to search all over for the solution.
Even though you've setup Calendar to sync with Google, the default is to have Google Calendar push calendar entries to your phone.
But on the phone, the default is to create new entries in "My Calendar" which doesn't get pushed to Google Calendar.
The effect of this is that you end up with a one-way Google to phone sync.
To have phone calendar entries sync to Google, you have to manually specify that when creating the entry: under the 'Calendar' section in the create event screen, tap 'Calendar' and choose your GMAIL account and not your phone's local "My Calendar."
If someone knows how to set Google Calendar as the default, please post a solution. (Maybe Froyo will fix this?)
Hat tip to Herbb623 for the tip found here.
Also, if you then want to sync to Microsoft Outlook, install Google Calendar Sync and all three calendars are synched.