I'd say it all depends on what's being advertised. It you just want to advertise your Dolphin website, that should be done in the community section. If you are advertising mods for sale or any type of service, there are places for that too. If you are advertising Christmas gift baskets... that's a definite sitewide NO.

If however, you are advertising helpful information and other useful things for no commercial gain, I'd say it's ok. Basically, I'd say that the blog section is no place to see more advertise for any type of commercial gain, or to use as a billboard to advertise your website, or any other type of self-serving interest.