I think when you set your google account on accounts tab in your phone and set it to auto sync, it synchronises contacts too.
I wasn't aware that Google keeps my contacts, couple of days ago, I accidentally erased them all, I was thinking how I can bring them back, but they all were in my google account.
So, actually you might try this. Save a fake contact to your phone, called "beer-in-box"

Then wait the phone to sync. Then go to contacts.google.com and see if beer-in-box contact exist in there.
Well, I hear what you're saying and I decided to give it a try...so here's what happened during my 'experiment'.
I had my SGS settings on 'Auto sync'.
I also had my computer logged into Gmail 'Contacts'.
1.) I created a contact called 'Beer In Box Test' and did 'Save contact to'...Google.
2.) I checked my Gmail Contacts list and 'Beer In Box Test' showed up. (This is to be expected...since I
told it to sync to my Gmail account.)
3.) I then created another new contact called 'Beer In Box Test 2' and saved it to 'Phone'.
4.) I checked my Gmail Contacts list and 'Beer In Box Test 2' never showed up.
5.) I then did a manual sync to Contacts AND sync to Gmail....and it still never showed up.
6.) I then created another new contact called 'Beer In Box 3' and saved it to 'SIM'.
7.) I then checked my Gmail Contacts list and 'Beer In Box 3' never showed up either.
Each time I even did a browser refresh of my Gmail Contacts !
Now as an interesting side note...in my SGS Contacts....the 'Beer In Box Test' contact name has been changed to 'Beer In Box Test 2'...and shows a LINK to 'Beer In Box Test' in Google.
Also, 'Beer In Box 3' shows up in my SGS Contacts as being in/on my SIM card. (This is also to be expected since that's where I told it to save it).
So, from what I'm seeing from this test....is that Gmail
only syncs and shows new contacts that were saved to your Google Gmail account.
It does NOT sync...nor show any new contacts that are saved as either to 'Phone' or to 'SIM'.

....and that's the name of that tune.
I hope others will find this report useful and I look forward to feedback from others. I will try to report any new findings I may come across.
I am considering doing an Import of the '.vcf' file into my Gmail account as has been suggested by another helpful poster.