Tips to help start your business blog (corporate blog):Starting a Business Blog - BBB Quick GuidesStarting a Corporate Blog?
Blogging for Beginners and Business Blogging 101 by Darren Rowse at Problogger - highly recommended.
Naked Conversations - Where Robert Scoble & Shel Israel wrote their corporate blogging book
Biz Blogging 101 Great repository of resources on NEWPRWiki
How to Start a Business Blog, Part I - A two part series from Bolder Blogs
How to Start a Business Blog, Part II
Starting a Business Blog? Here Are a Few Questions You Need to Answer
Starting a Corporate Blog? - Good post by Owen Lystrop
7 Questions To Ask Yourself BEFORE Starting A Business Blog
Starting a Business Blog: Remember the Planning Phase
Check out Easton's series called Corporate Blog Reviews to find out what your competition and other businesses are up to.
This is just the beginning so please let me know if there are additional posts that need to be added.
PS - Here's a post on some poor corporate blogs: The worst Fortune 500 blogs - Part I