Earlier today Glynn Foster blogged a question here that boils down to "Why don't Jonathan Schwartz and Scott McNealy blog?". Interesting question, Glynn, which I thought I'd give a shot at answering.
First of all, despite all assurances to the contrary, it takes a bit of time to maintain a successful blog (I speak from experience, since I don't write *nearly* often enough myself when I'm traveling). Executives are pretty busy and hence many routine tasks get delegated to assistants. Have a look at the Bush/Cheney '04 Campaign Blog for an example of this problem. At least there are no pretensions that George W. Bush is actually writing this blog, but its pretty dry reading and indicates a misunderstanding of what makes a blog compelling: Authentic Voice. Nobody makes this point better than the Cluetrain Manifesto.
"But learning to speak in a human voice is not some trick, nor will corporations convince us they are human with lip service about "listening to customers." They will only sound human when they empower real human beings to speak on their behalf."
Not that the Bush campaign isn't trying for a human voice (check out the Presidential Cookie bakeoff. Can't you just see Laura Bush whipping up a batch?) For comparison, check out Kevin's Polemics blog, a fine example of what I would consider an authentic voice.
Second, there are good reasons why executives, as legal officers of an organization, have to be very careful what they actually say in public. Extending the Presidential example (and assuming that the President actually had time to blog) imagine pundits combing over every entry looking for clues to his state of mind on any number of issues. Imagine fluctuations in the stock market if every Presidential blog were analyzed for references..."That's the third time this month he's mentioned having Oatmeal at breakfast instead of Corn Flakes...Oat futures are on the rise". Extend your consideration of this issue and you'll see that it would be pretty hard to write a casual blog (as Microsoft blogger Rob Scoble said recently in his comments on self-censoring).
Third (and not to be underestimated) is the cultural shift involved in blogging. For many many years official caution in public communication has been the norm. Sun has gone so far as to famously issue a new official policy to encourage open blogging, but its definitely still a new concept to most Sun employees. There is a blogspace behind the Sun firewall and some executives (notably John Fowler) are starting to show up there. And of course there is at least one Sun VP and Fellow with a public blog, James Gosling.
So, while I agree with Glynn that it will be a great thing when the senior Sun executives start blogging, it may be awhile before we see lots of spontaneous executive blogs. Still the medium is creating a shift inside Sun and other companies. Traditional assumptions and practices are being re-examined, which was one of my hopes when I and others started promoting the idea of blogging to Sun.