There also is an international list of CEO bloggers at the New PR Wiki, but you'll have to extract the Fortune 500 companies yourself.
Both wikis demonsttrate the fact that no blog search engine, including Technorati and Google's, is particularly comprehensive or well-organized cross-referenced.
When, oh when, will someone do a blog search engine right?
About BL Ochman B.L. Ochman, Managing Director of Emerging Media for Proof Integrated Communications, the digital marketing arm of Burson-Marsteller, has been helping Fortune 500 companies strategically incorporate new media into their marketing mix since 1996.