As you might have heard a number of Microsoft proprietary protocols has been opened up (incl. the protocol used for Microsoft Exchange Server) as reported on Slashdot and on Redmond Developer News. This would make it possible, as actually mentioned in a Notes 8 session at Lotusphere 2007, to make Notes 8 a client for Exchange since the Notes 8 client (read Lotus Expeditor) is actually very generic.
But then again who would want to run against Exchange Server? 😉
Via the Java Posse episode 110.