Google, Yahoo! crawls .swf files
This has been a major obstacle in the past due to the fact that if these search engines do not recognize your work, basically you don’t exist. Now designer and developers can style and architect with the peace of mind of being searchable. This includes Flash “gadgets” such as buttons or menus, self-contained Flash websites, and everything in between. All of the text that users can see as they interact with your Flash file. If your website contains Flash, the textual content in your Flash files can be used when Google generates a snippet for your website. Also, the words that appear in your Flash files can be used to match query terms in Google searches. Keep in mind, URLs that appear in swf files, and feeding them into Googles’ crawling pipeline—just like they do with URLs that appear in non-Flash webpages. For example, if your Flash application contains links to pages inside your website, Google may now be better able to discover and crawl more of your website/RIA.
This is a major improvement for the RIA world, because competing RIA technologies to Adobe Flex and Flash are not crawl-able by search engines like Silverlight. As with HTML content, best practices will emerge over time for creating SWF content that is more optimized for search engine rankings.