Nice article. In response to the last part I can think of a way to achieve the sort of smart escaping via template you talk about using Haskell and Hamlet (among other templating systems used by yesod). I believe, although I can't absolutely confirm that Hamlet already performs context appropriate escaping, based mostly on the type signatures and the names of a few of the functions.
Yes, Hamlet does context specific escaping. It will handle all the examples given, except you can't mix your javascript in with your html (which is generally good advice anyways).
I disagree with the articles premise that injection is always a display issue. In the [Yesod web framework](http://www.yesodweb.com) which uses Hamlet, we sanitize, not strip html by default before it is ever put in the database. The more you can make injection not a display issue, the better- you just have to know your options.
