SEO Tip #39: How can new pages get indexed quickly?
Matt Cutts: Well the simplest answer is to get more links.
We can index a page within second, certainly within minutes, if we find, for example, that CNN is linking we’ll crawl that very, very quickly. So we can find new content quite quickly. If you have a blog or something like that we’ll come back pretty often and check for it.
But the best way is to make sure that you have enough links that we think you are really a useful site and that we come back pretty often.