Microsoft Active Directory (ADS) uses Kerberos for single sign on. As soon as you login to an domain you get a Kerberos ticket. So it's actually quite wide spread.
Yes, I have setup Java and Apache servers to do authentication with Kerberos. The support is quite mature now. The only hassles tend to be with the Windows servers and PCs deprecating weaker algorithms which require tweaking krb5.conf and occasionally digging into AD attributes.
