One of the confirmations I have had is that the big sites like Flickr, Wikipedia, Facebook and others don't use exotic setups when it comes to their hardware and OS. During a keynote panel, they all commented that they did not do any virtualization on their servers. Most did not use SANs. Some ran older MySQL versions but some were running quite recent versions. I have kept thinking that I did not have the desire to get to fancy with that stuff and clearly I am not the only one.
One of the little nuggets that will likely change my world is index_merge in MySQL. I feel silly as this has been around since 5.0.3 but I was not aware of it. Basically MySQL will now use more than one key to resolve a where clause and possibly an order by depending on the query. This could lead to me removing several keys from tables in both Phorum and at dealnews.
There were others, but I am tired and trying to get OpenID into the Phorum trunk right now so I will have to think of more later.