I too would be interested, I was at NetApp when they acquired Spinnaker which was using Linux and that product was ported over to FreeBSD. That said NetApp has been a huge supporter of getting solid NFS support in Linux both through the pNFS effort and the work that was done at Citi/UMich.
That post is 6 years old and ONTAP has been through at least 3 major releases since then.
Additionally, the post states that the purpose of ONTAP on Linux was to simulate ONTAP for testing & education purposes. In 2006 this was probably the easiest way, but those needs have been met for years by the VMware images NetApp provides.
Cisco bought an existing company, and the product is stagnant.
Citrix bought an existing company, and the product is stagnant.
F5 went to Linux many years ago
Juniper is still FreeBSD. They win this one ;)
NetApp has a port to Linux, but is still shipping FreeBSD. 50/50.
Nokia/CheckPoint went to Linux (SecurePlatform)