Most visitors arrive at your blog in one of two ways:
The search visitors found you, likely for the first time ever, because something you wrote came up as the result of a search. These are the folks for whom you need to refresh old blog posts, because a popular older post may be all they ever see of you.
Search visitors who really, really like what they see (such as relevant information that you have obviously taken trouble to keep fresh), and who think that you might have more interesting things to say in future, may become:
Regular readers - those who know and like you, and have made a commitment to you: they visit you regularly via bookmarks in their browsers, or have subscribed to your RSS feed in a feedreader so as to be alerted when you've written a new blog post. These are the source of much, though not all, traffic to your main page (blogs.sun.com/yourblogname/); whatever is on that page that day (i.e., your most recent article) is what they read.
How can you best serve your regular readers? Be regular yourself! You don't have to write every day or even every week, but try to set a minimum schedule that you will be able to stick to, and set expectations appropriately with your readers.
Otherwise, if someone comes back to your blog day after day or week after week, and keeps finding nothing new - well, it's disappointing. Eventually they stop coming. They feel abandoned, and they abandon you in turn. If they follow you via a feedreader, they'll unsubscribe - isn't that what you do when a feed just sits there, month after month, and never gets updated?
What if you're really, really busy and just don't have time to blog? Let your readers know! At least give them a line or two to tell them that you haven't died or left the company, that you still care about them, and maybe you're even busy with something amazingly fantastic that you can't wait to tell them about, just as soon as you're able... You might be surprised at how much a little note like that will mean to your readers. And they'll stick around, eagerly awaiting that big news you promised!