After having just migrated a customer from Web Interface 3.0 + Secure Gateway 2.0 to Web Interface 5.1 / Secure Gateway 3.1.1 I had the unfortunate pleasure of finding a memory leak in Secure Gateway 3.1.1.  After some period of time (hours/days depending on how busy your SG environment is) the private bytes in use by the Secure Gateway service climbs to a point where it stops functioning.  When this happens you're down.  What's worse is that if you're using traditional port monitoring on a hardware load balancer, the SG Service still listens on 443 so your load balancer won't direct users away from the non-functional Secure Gateway host.  About three days ago Citrix pulled the Secure Gateway 3.1.1 download as visible on CTX121012  However that doesn't help me much since my customer was turned up a few days prior to it being pulled UGH!.  Anyway, I'm now in the process of uninstalling SG 3.1.1 and installing 3.1 in it's place (which sucks because 3.1 has a security vulnerability).  Hopefully Citrix will put out a fixed 3.1.1 release and more importantly hopefully they start communicating these types of things through their blog, etc.

UPDATE:  Citrix has released Secure Gateway v3.1.2 that resolves the memory leak.  Get it at CTX122212.