Citrix Xen App
Version 11 of the Citrix Xen App has been out for a while, and the nice folks over in freebsd-emulation@ recently got the linux-f8-* stuff in place so I could deliver it. It will be offered as net/citrix_xenapp, and I will keep Citrix 10 around as net/citrix_ica for a little while longer.
Please note Citrix Xen App requires the linux-f8 emulation, and it is documented to be problematic on on 7-FreeBSD. Ideally you need to run it on 8-FreeBSD (or better). That said, I am personally running it on 7.2-STABLE, but it requires a little tweaking. Herein I will document what you need to do to make it work. I cannot guarantee that this will not fry your motherboard, change the outcome of your favourite sporting event or upset the balance of power in a small third world nation. USE AT YOUR OWN RISK
For 6-FreeBSD
Sorry, no help here.
For 7-FreeBSD
You need to fool the OS that it is a higher linux release than it really is.
From the command prompt issue the following statement
# sysctl compat.linux.osrelease=2.6.16
and add the following line to /etc/sysctl.conf
compat.linux.osrelease=2.6.16
You need to be running linux-f8-*, I tried linux-f10-* and it did not work 
Add the following two lines to your /etc/make.conf
OVERRIDE_LINUX_BASE_PORT=f8 OVERRIDE_LINUX_NONBASE_PORTS=f8
For 8-FreeBSD
bsam@ has set f10 as default, http://lists.freebsd.org/pipermail/freebsd-current/2009-June/008568.html. I have not yet tested it, but it should work.
Now you can
cd /usr/ports/net/citrix_xenapp make install && make clean
Distfiles for citrix_ica
Yes, I know that Citrix seems to have pulled the version 10 tarball from there website, ping me, and I can help you out