I've run into a few applications that simply assume Java is installed. They die horribly with a "javaw" not found.
My first inclination is to just pop up a message explaining what went wrong and how to fix it, with a clickable link to go Sun's Java download page.
This struck me as similar to the Gecko situation. In principle, we could have a wine-java package containing Sun's binaries and then just install them automatically when they're on the system, referring the user to the website otherwise.
Distributions would then need to make these packages (just like wine-gecko), and also get separate permission from Sun. This strikes me as rather feasible - Ubuntu already ships Sun's Java in its parter repository - however we'd need to work out how it would work technically here first. Ideally, Sun's installer wouldn't need to be modified.
Thanks, Scott Ritchie