FriendFeed uses MySQL to store "Schema-less" data

Came across an interesting post by Bret (co-founder of FriendFeed) about how FriendFeed uses MySQL to store "schema-less" data. According to the post, they weren't having issues with scaling existing features but rather they were experiencing pain when trying to add features.

Now the way they are using MySQL is interesting and bizarre at the same time. At a very high level, it seems their approach is to use a RDBMS as if it is a column-oriented database. Of course, it makes me wonder why not just use a column-oriented database? I need to read the post again in the morning (too tired right now so just gave it a quick glance).

I am very interested in hearing thoughts from my peers at Planet MySQL regarding this approach. They seem to have gone great lengths to go this route. What issues and benefits you see of this approach and whether you ever see yourself taking this route? I, for one, am not entirely convinced of this approach and whether it can really scale down the road. Also, if it was someone other than Friend feed going down that route, I might have actually lost my tempered and yelled :)

Side note: Friendfeed is growing fast, and it would have been cool if Bret was speaking at one of the three upcoming MySQL events in April.