This has always been a minor pet peeve of mine with .NET CF and the default Smart Minimize action of a form...sure it's easy enough to override, but the misleading use of an "X" for "minimize" was what always got me.
Mike Calligaro on the Widows Mobile Team Blog has posted a pretty exhaustive blog entry regarding the whole deal which is well worth reading. It's called The Emperor Has No Close.
Enjoy!