ICE (International Contemporary Ensemble) has become a fixture at what might once have been considered and unlikely event, Lincoln Center's Mostly Mozart Festival. In recent years it has devloped into a more eclectic sort of festival, grounded in the music of Mozart as always, but including baroque and classical music played on period instruments as well as contemporary music. Within a few weeks Mostly Mozart provides a condensation of our musical interests today. It is especially welcome to get some taste of the rich contemporary music life in the City, when it inevitably thins out for the summer, as composers, many of whom teach for a living, go off to the country or an arts center to compose, perhaps with a visit to the Festival of Contemporary Music at Tanglewood or some other opportunity to congregate with colleagues and hear each other's work.