I use Mac OS X 10.6.4 (10F569). Today October 8th the iCal icon in the dock show the number 7. If I open iCal, it shows correctly Friday 8 and the iCal icon updates to the right day number. When quitting iCal, iCal icon in the dock come back to 7... System time is correct and synchronized with ntp server.
If I create new user, the date in the iCal dock icon is correct. However, in my user, today happens the same, icon show 10th but now is 11th. I also check the time zone, it's ok. The strange is that the date in the menu bar is ok, only iCal dock icon is wrong!
Ok so the issue is user specific. So nothing wrong with iCal here. One or more files in your user account have been modified and their are causing iCal's icon to behave strangely.
Go to Apple Menu > System Preferences > Language & Text > Formats > Region. Make sure this has a country name in it, not "custom".
If that does not resolve the issue then:
Backup iCal by going to File > Export > iCal archive.
Quit iCal.
Remove the following to the trash and restart your computer:
Home > Library > Caches > iCal
Home > Library > Calendars > Calendar Cache, Cache, Cache 1, 2, 3, etc. (Do not remove Sync Cache or Theme Cache)
Home > Library > Preferences > com.apple.ical (There may be more than one of these. Remove them all.)
__NOTE: Removing these files will remove any shared (CalDAV) calendars you may have access to. You will have to re-add those calendars to iCal > Preferences > Accounts.
In Language & Text > Formats > Region I have Italy (Italian), also changing this doesn't resolv.
Then I tried to remove caches, but Home(user)/Library/Caches/iCal doesn't exist and neither /Library/Caches/iCal. Doesn't exist also Home/Library/Calendars...
