With these site launches I have noticed some interesting patterns. All of them which I set to ping Google blog search were spidered within minutes and the site was in their index within days. On the sites which I did not ping Google, the sites took weeks to get indexed, even when I pointed strong links towards them.
WebmasterWorld has a thread where some people are noticing similar patterns on more established sites. They claim to have posts from established blogs in the index within hours, not days.
The only negative side affect I can find has to do with supplemental results. These where brand new sites, most with only a single link from a forum post. So even though the sites where indexed at warp speed, within a week many of the pages went supplemental. This probably won’t be a problem for established sites or sites that actively link build from the start.
This could even be adapted for non blog content. I believe most CMS software has some form of ping system addon these days. If not, you could always have it added yourself.