I have a two node UAG NLB (multicast) array setup. the servers can ping the internal exchange hub/cas 2010 servers, and if the servers are not in the array the OWA trunk connects to the servers and works.

now that my servers are in an NLB they OWA has stopped working and i am getting a no web farm server is available for the OWA request when i attempt to make a connection. 

my two UAG boxes are hosted on VMware 5.1 ESX hosts and are version 4.0.3123.10000

Could this have to do with setting the static arp?

I believe that using Multicast is only supported for UAG DirectAccess connections. UAG portal connections are only supported under Unicast mode.

http://blogs.technet.com/b/ben/archive/2012/10/26/nlb-modes-supported-by-uag.aspx

That being said, when you create NLB the MAC addresses are replaced with a virtual MAC address. This does very often screw up "smart" switches, and you need to clear the ARP cache on the switches to get traffic flowing again after establishing the NLB. This happens to me all the time during DirectAccess deployments.