I once blasted some links at a domain for a period of 3 weeks and during that time the crawl rate of the site was so frequent. Im talking, at least 2-3 times a day they cached the site. This means, with any progressive backlink campaign or increase in backlinks (obviously since their spiders keep revisiting the site to find out what all the fus and hype (newly acquired backlinks) is about..the spiders are thinking there might be some useful or gem-like super content on the site that causes this recense influx of backlinks. in other words, with new backlinks, G EXPECTS to find new content on the site. Therefore, I conclude that regularly updated content and regular newly acquired backlinks are needed. They both go hand in hand? Any fellow members want to add to this observation?