That's; all over...
January 13th 2010...
No more NAV 4.0 sales, no more fixes, no more work on it - MS Dynamics support is finished for NAV 4.0 (all versions).
Dynamics NAV 4.0 SP3 still could be downloaded from
And latest build (latest fix) could be got as described at http://blogs.technet.com/gediminb/archive/2009/03/26/available-nav-hotfixes-download-using-kb-article.aspx