Sorry for the delayed reply.
Firefox(11.0): the mouse scroll wheel works as expected.
Chrome(18.0.1025.162 m): Absolutely nothing happens on the page, in the map, nowhere when I use the mouse scroll wheel. I have tried Flex applications from outside our organization and had the same experience.
I have not tried adding mouse scroll event listeners. Will try that and also look at the javascript.
If other people are having Zero trouble with Chrome using the mouse scroll wheel to zoom in and out of the Map within a flex app, please let me know, too! This isn't a showstopper or anything, just irritating.
By the way, I have a javascript application where the mouse wheel works fine within Chrome.
Thanks,
Carmen