REPLACE INTO table a la mySQL

I know we're not in the business of copying mySQL,
but the REPLACE INTO table (...) values (...) could be
a useful semantic. This is a combination INSERT or
UPDATE statement. For one thing, it is atomic, and
easier to work with at the application level. Also
if the application doesn't care about previous values,
then execution has fewer locking issues and race
conditions.

comments?

Dale Johnson