I'm a bit skeptic, some of my sites are getting crawled & indexed within minutes after update, don't see how 1 minute would help. Is there any good resource to read about pinging?
That doesn't convince me to be honest
Based on my observation, ping services do help your blog crawled or visited faster, I notice it unintentionally on 2 of my blogs, one with ping lists provided from WP install and another with ping lists I got from WP forum (a lot more ping services), the one with list from the forum got indexed faster than the other one.
I know it's not really justify anything since there are many other factors in effects such as keywords popularity and all but I personally believe that ping services do give a positive effect.
Adding a ping list is good but I think before you add a ping list to your Wordpress Blog, you should install a ping optimizer plugin like Maxblogpress Ping Optimizer or Cbnet Ping Optimizer. Since Wordpress ping each of the services, each time you update a post. It can get you banned from the services for repititive pinging. Installing those plugin will stop Wordpress from pinging the services for a certain period of time
what happens when some of these links don't work anymore as a ping site?