Flash designers might rejoice that Google does index flash sites. But for the webmaster, bear in mind that Flash sites will require a lot more tweaking than HTML pages to get a content-based site rank high. Search engine crawlers use your site’s text content to determine relevancy and while Google can now parse SWF files to see textual content in the file, most Flash animation just make it difficult if not impossible for Google to make out the text right.
Most, if not all, Flash developers enjoy breaking up text and graphic elements for animation effects and this can confuse Google’s parsing algorithms.
If you need to have that fancy Flash for your website, try to discourage your Flash developers from too much text animation. Flash is perhaps the best thing to happen in making your website look great. But just don’t expect to get great SEO results.