I was not at this session at Webmasterworld about organic site review but Vanessa Fox (who I spoke with a couple of times at the WMW conference) was and made some pretty good notes - and I’m including those notes here.

Flash-based sites
It’s not only Googlebot who doesn’t watch a 20 second video load before the home page comes into view. A lot of users don’t either. Some users don’t want to wait that long; other users don’t have Flash installed. If all of your content and menus are in Flash, search engines may have a harder time following the links. If you feel strongly about using Flash, just make an HTML version of the page available as well. The search engine bots will thank you. Your users will thank you. Feel free to block the Flash version from the crawlers with a robots.txt file, since you don’t need your pages indexed twice. If your home page is Flash, put the navigation outside of the Flash content. You could offer a choice on the home page so users can choose either the HTML version or the Flash version of the site. (You might be surprised at what users choose.)

I see so many sites ramping up on Flash without thinking through the consequences.