So here's the condensed version: Of course it's important to publish frequently! I firmly believe that publishing your best work AS FREQUENTLY AS POSSIBLE is critical to your blogging success.
Of course there are exceptions, most of which would have to do with the subject nature of the blog in question.
But in general, more posts means more chances for others to read your work and comment about it and post about it and talk about it. More posts means more evidence of your own work as an expert, as a thinker, as someone who genuinely cares about something enough to say something about it.
Quantity versus quality? Here's my answer: Post the best you can, AS OFTEN AS YOU CAN. The world of blogging - especially of business blogging - is not for those who spend mothns drafting that one perfect post and then hit the rusty publish key hoping that the world will suddenly take notice. Nor, of course, are the best bloggers necessarily the ones with the most blogorrhea (i.e. the most frequent posters). But there's a happy medium there, which I feel leans somewhat toward the "more frequent" end of the posting spectrum, that I think business bloggers should strive for.
I can't tell you how many corporate blogs I read that I stop paying attention to simply because they don't publish often enough to keep me interested. I regularly unsubscribe from feeds that haven't updated in a while.
Don't worry too much about posting frequency. But do make it a priority to post as frequently as you can without lowering the quality of your posts.