Any Thoughts ??????????????????????????

Web service.............................

As a developer, I would recommend developing an event handler solution to do
this. You can use the SharePoint object model to do all of this.  Just make
sure that when you update the other site, use elevate privileges.

So you're not using variations then?

office.microsoft.com/.../about-source-variations\
-HA010121299.aspx

I'm not sure where is your problem.

Do you want to synchronize to entire site ? Or just some contents with filter.
Can you explain what you need fonctionnaly ?

Technically ,You can write your event handler as any other one.
When need to create a list item in another site, use :

Using (SPSite site = new SPSite("http://myurl/site/subsitefrench")
Using (SPWeb web = site.OpenWeb())
{
...
/// create your listitem
}

Let me know if it help.

I have English site and French site, both sites have the same structure (list,
doc lib, calendars ... etc), what I want again is that I need
to synchronized both sites, what ever I do in one of them then it should
be reflected automatically in the other one (Add, Edit, Delete).

I think that the suggestion from Nicolas is a valid one and I suggested
web services.

Nicolas idea is best in light of the request. Add those event receivers to
each and every list.

what kind of webservices ? do you have some samples ?

Check out SPServices, though I think your best bet is to go with event handlers.

Any details on how they are set up. Are they completely different Web
applications or did you utilize the multilingual publishing capabilities?