There is a lot of talk now about SDN, so I would like clarify what is actually meant with SDN.
First of the name SDN is for Software Defined Networking, the concept Is actually pretty simple. It is built upon that a network administrator can share traffic from a single console Instead of having to configure each switch individually.
And for instance, it allows for an admin to allow SharePoint traffic but not regular HTTP traffic, it steps away from the regular ACL deny/grant and performs at a more granular level.
Hence the name, Software Defined 
So you have to think that instead of configuring the switches, acls, router etc., an it-admin configures the software that goes trough the network(application control)
So there is a lot of speculation that this is going to be a Cisco killer or Cisco kill switch because this would allow for a multi vendor solution but still have that single control plane.
So again the network becomes app-driven
And back to the topic, Citrix has already laid plans for the future with its Netscaler product and SDN.
They have already established many partnerships with different vendor for this to happen.
Cisco has announced that they are going to discontinue their production of their ACE module, and has already gone into partnership with Citrix to work with SDN.
They have that that for instance Netscaler and their Cisco ASA (Their firewall product) will include integrations which are based upon SDN.
Citrix has also aligned themselves with a lot of other partners such as.
* Palo Alto
* Trend
* Aruba
* WebSense
* Bluecat
* RSA
* Splunk
You can read more about them here –>
http://www.citrix.com/products/netscaler-for-sdn/how-it-works/partners.html
And Citrix themselves has a lot they can offer with Netscaler
With for instance AppTemplates they have many finished templates a company can use (For instance SharePoint, Citrix has made their own template based on best practices which allow for the best kind of user experience )
a template can include (policies for caching, compression, rewrite and other NetScaler functionality used to optimize the application.) So instead of typing in all the information all the Netscaler needs is the IP of SharePoint and Netscaler will do the rest, pretty easy instead of writing ACLs, setup up the service adding load-balancing etc.
You can find them here –> http://community.citrix.com/display/ns/AppExpert+Templates
So it’s a step in the right direction
And with integration with System Center, an Netscaler deployment infront. a Netscaler can detect if there is need for more servers in the back and automatically deploy more.
But the conclusion is, SDN is become more and more popular subject so be ready for it