is this black hat seo?

[Kim Cunnings]

He should stop doing that right now, this is completely and entirely black hat and will get the site penalized and deindexed. There was a recent Panda update by Google, as a result of which G has removed a ton of sites that lack in content. Since those no-content blogs link directly to your boss's site, the Google bot can easily trace the connection and decide that if the blogs are rubbish, the boss's site is rubbish as well. No good will come out of it, trust me.

Tell your boss that links should be thematically relevant to his website's subject and that he should build links slowly, not overnight.

More on best SEO practices on Dan Richmond's SEO in Practice, a free and informative read. Google webmaster forum is a great source as well. Your boss should read those before getting into hot water with Google.