In the phone app it shows call times for today and dates for earlier calls.
If you highlight a call and use "Menu>View History" then it shows you the entire history of your calls to/from/missed for that number with date, time and status.
Finally, if you go to Messages and use "Menu>View Folder>Phone Call Logs" it will show you about a month's worth of back history on your calls laid out like any of the message lists - broken into sections by dates with time, name, and status on each line.
I checked my call log today on my 8320 and noted two calls made on 10/24/07 to a contact in my address book that I know for a fact were not made. I also checked tmobile.com and can see that these calls do not appear on my account.