Are there any teachers experimenting with an immersion model in a High School setting?

A growing body of research on immersion education has shown that immersion
students consistently meet or exceed academic expectations in the following
areas:

* Second language skills: Immersion students by far outperform students
in traditional foreign language classes. They are functionally proficient in
the immersion language and are able to communicate according to their age
and grade level.
* Content areas: Immersion students achieve in academic areas as well as
students in English-only programs.
* Cultural sensitivity: Immersion students are more aware of and show
positive attitudes towards other cultures.

Having said that Robert DeKeyser's research is worth looking at.

http://journals.cambridge.org/production/action/cjoGetFulltext?fulltexti...

Robert DeKeyser has worked with the 'critical period' theory to understand how cognitive development affects Second Language Acquisition. After a “critical period,” typically near adolescence, the brain functions differently while acquiring a new language. Before this critical period, the brain learns a second language much like it learns the first language; after this critical period, the brain works differently. Understanding the psychological differences before and after the critical period can help improve SLA instruction in both K-12 education and in adult-learning contexts.

A young child tends to absorb a language through massive amounts of input and exposure, while explicit learning, rules, practice and grammar, plays an important role for adolescents and adults. (Munoz, C (2003) variation in oral skills development and age of onset)

Early immersion for young children leads to native-like language ability.
(Johnson, J.S. 1989 – Critical period effects in Second Language Learning)

The important thing to remember is that effective language teaching needs to be age appropriate. Young children appear to learn well with full immersion that imitates growing up in a language. Older students require grammar and structure along with meaning and conversation. Of course a teacher will be sensitive to the needs of the learners, but research tends to suggest that the older the student and the more complex the language, direct teaching outside of the immersion model gets better results.

Having taught both young learners and High School students, this tends to
support my own teaching experiences.
Has anyone else tried immersion with High School students?