One of the criticisms of Closure Templates:
"- Very little usage outside of Google. No plans to push new versions
or accept new contributions."
is no longer true.
They also left security entirely out of that matrix -- how much work
do you have to do to write a web-application that is more-or-less
correct, more-or-less complete, and robust against XSS.
http://code.google.com/closure/templates/docs/security.html describes
the closure take on this.