Is it possible to use Safari4 with an IIS hosted Intranet site that uses IntegratedSecurity (NTLM)? InternetExplorer and Firefox are capable of dealing with it. I couldn't find a way to get it working with Safari though.
Short answer. No
The webkit engine does not have a way to deal with NTLM as yet, and there are no plans as far as a I am aware for this.
SharePoint has built a workaround for this in the way they handle cookies in SP2 and in 2010 for example, to allow the server to 'think' that the browser is NTLM authenticated.
I have been investigating this for the last 6 months, we have 150+ Mac users that need access to SharePoint for example, and Safari is my personal favorite browser
The current version of Safari (5.0.5) does have support for IIS using Windows Integrated Security.