I won’t even confess how long I’ve tried to get Mac iCal to sync with the corporate calendar (for 4 years it was Groupwise, and more recently Oracle Calendar, ok I confessed!). And then to complicate matters, I recently got an iPhone.
I also won’t go into the gorry details of getting to the solution (really I won’t). But here’s what I’m doing
– using a nifty app from Synthesis AG called Todo+Sync task manager. This syncs to the SyncML server at University of Manitoba (thanks to the help from Brian Goodman at IST at U of Manitoba). (check the settings at http://www.umanitoba.ca/computing/ist/accounts/calendar/syncml.html but for the calendar folder use ./Calendar without the slash Events). That gets my Oracle Calendar to my iPhone very nicely.
– using SyncJe for Mac I can sync my Mac iCal and the Oracle Calendar.
And it seems to work! I know that it seems a bit crazy that I have to have licenses to three pieces of software (Oracle Calendar, Todo+Sync, and SyncJe) to do what one should do, but oh well (insert shrug). I think this way I can skip needing MobileMe. And I can use Mac iCal which I like.
Revised POSTSCRIPT: I am having issues with syncing repeating appointments with the SyncJe program. I think Oracle Calendar might be very fussy about appointments that were made in Mac iCal without a location. For now I am just working on getting my Oracle Calendar cleaned up and getting the syncing working with my iPhone, then I’ll do some troubleshooting on the syncing with Oracle Calendar and Mac iCal.
I found a great help page at UW-Madison
Count Your Blessings 
Hmm, I simply export my Oracle calendar at the end of the day to Dropbox, then at home import into iCal, then sync the iPhone. I’ve considered writing an applescript to automate the import into iCal, but it’s a pretty simple process, and free!
That works if you use Oracle calendar, but I use iCal for my main calendar.
Did you ever solve the problem with reoccurring events? I’ve been working on that a while now to no avail. The SyncJE tech support can’t do anything without access to my campus server and that isn’t going to happen. Thanks.
No, I gave up. I just stopped using Oracle calendar, and got a mobileme account. I’m just about out the door of University of Manitoba and going to an institution that uses Groupwise, so looking forward to a whole new set up syncing problems (not). Good luck though!