Why do blogs get indexed so fast?
Good question me Lord, let’s see how fast this crap gets indexed in ye ole Google shall we? Clocks ticking and im still typing. Wouldnt it be nice if we could get all content indexed soo fast~ what is soo amazing about a blog anyway? Na na na na naa
A few possible answers are:
XML RPC Ping, which pings servers to tell of updated content. Another is Google looks at the /wp-admin part of WordPress blogs. Because let’s be honest, Google is in bed with WordPress.

12.44 AST
The answer to your question appears on the right side of the page – an archive of ORIGINAL, QUALITY posts that generates volume. You are running a very good blog
Thanks Michael, keep up the good work
Blog are nothing but the fresh and updated content.So it is easier to index and the process is very fast.
So going back to this it is based on RPC or RSS.