Until recently, it was basically impossible. One good reason to avoid Flash features on your corporate site has always been that they don't get picked up by the search engines. Historically: they've been impossible to index.
One woman's opinion: I think it tends to be over-produced eye candy that doesn't deliver the stickiness to your site that one would hope. But, I'll leave that point for another day.
Meantime, the search engine issue has finally been laid to rest with Yahoo! and Google both announcing their search engine spiders can now detect flash sites and index them to show up in their rankings. This is thanks to new technology provided to both companies in partnership with Adobe.
Here's Google's write-up on their webmaster blog.
I still think Flash bits are more often than not over-produced eye candy.