Cookies are currently only loaded once from disk when the application start. They are never reloaded latter, this means the cookies are not really shared between processes. The problem is however that the quirky lookup and parsing of cookies is not easily expressible as SQL queries.
Can you point a specific use case where that would be a problem? The only thing I see is if multiple instances of an application would need to share the cookie jar, but I don't see an easy way to solve this. It's probably easier to use a single application model than trying to get all instances to be notified when another instance has a new cookie to share in their web/network process. The real solution to this could also be that a service on the OS is taking care of handling cookies for all applications.
=== Bulk closing of Qt bugs === If you believe that this bug report is still relevant for a non-Qt port of webkit.org, please re-open it and remove [Qt] from the summary. If you believe that this is still an important QtWebKit bug, please fill a new report at https://bugreports.qt-project.org and add a link to this issue. See http://qt-project.org/wiki/ReportingBugsInQt for additional guidelines.