PuSH support is turned on for every Wordpress hosted blog. PuSH a realtime protocol designed to speed up RSS. It stands for Pubsubhubbub, PuSH sends the content of blog with the notification via so-called fat pings. Google Reader also supports PuSH,
PuSH is a way for services that subscribe to updates from your blog. With PUSH new posts get pushed out to feed readers within the second they are published.