Please note this is only a problem if you're trying to prompt the upload from outside of Flash, or without a user action to cause the prompt to appear.
For Flex applications that have an upload button, for example, this should not be an issue. As long as the upload prompt is called from within a user-generated event (i.e. the user actually clicked on something, which raised an event, which ended up arriving at your code), this will not interfere.
Ah, nice. We use SWFupload in our PHP apps and a different Flex uploader in our Rails app. Not sure if the Flex uploader is affected by Flash 10. I'll have to check it out.
The new YUI release now includes a flash uploader that works with Flash 10.
Can be used in two ways: Either you configure a sprite that the flash uses to show the button, and the user clicks on the flash button, or the flash inserts itself as a transparent overlay on top of the existing upload button.
Works well, though getting express install to work with the YUI script takes a bit of hacking...
For Flex applications that have an upload button, for example, this should not be an issue. As long as the upload prompt is called from within a user-generated event (i.e. the user actually clicked on something, which raised an event, which ended up arriving at your code), this will not interfere.
Also, this has been well-known for some time.