This link might be helpful to give more information about each particular property: http://msdn.microsoft.com/en-us/library/aa384372(v=vs.85).aspx
From Microsoft definition they say the following:
Allows the client to use Negotiate authentication. Negotiate authentication is a scheme in which the client sends a request to the server to authenticate. The server determines whether to use the Kerberos protocol or NTLM. The Kerberos protocol is selected to authenticate a domain account, and NTLM is selected for local computer accounts. The user name must be specified in domain\user_name format for a domain user. The user name must be specified in server_name\user_name format for a local user on a server computer. The default is True.
That definition suggests that kerberos is supported, also if it wasn’t then -credential shouldn’t work when authenticating against another domain.
Unless i haven’t understood something properly here - hopefully someone else can correct me.
Do you have the articles where they suggest it isn’t?