I've seen some blog posts indexed within 2 minutes. A lot of people have reported sub-5-minute indexing. 20-40min is good and the most common time frame in my experience and from what I understand from other people.
Ultra-fast indexing depends on posting just before the crawler hits the index page. A lot of luck is involved to catch the crawler like that.
If someone uses Google Reader to subscribe to your RSS feed, then your new blog posts are likely to get indexed as soon as Google Reader sees your new post show up in RSS.
Ultra-fast indexing depends on posting just before the crawler hits the index page. A lot of luck is involved to catch the crawler like that.