…That said, you will see some really great uses of Avalon in Longhorn. The clock that we shipped at the PDC is built in Avalon, for instance. There will be plenty of examples to prove to you that it’s ready for serious app development.
Well, clock samples are no sign that Avalon is ready for serious app development. Neither are NotePad clones etc. Avalon will be ready for serious app development if a major app like Outlook can be written with out-of-the-box controls & widgets supplied by the UI infrastructure of Longhorn.
Out-of-the-box? Yes. Because, for the sake of consistency, lots third-party developers will try to mimic the UI of Microsoft apps. And it’s neither in their nor in Microsofts best interest to re-invent the wheel.