My thoughts on the subject (from March 2011):
I personally think that this is a neat idea but VoiceBunny isn't the ideal tool. You pay about $70 for 400 words which is about the length of a short-mid sized blog post. If you just cover 5 posts per day, you will need to invest about $10k per month in VoiceBunny. At this point, looking for your own voice actors is probably cheaper.
Great idea btw, would love to be a part of it.