Update: WordPress released an updated PubSubHubbub plugin called PushPress that actually makes your site the PuSH hub, so this is a better choice than the plugin I linked to below.

Google just announced support for PubSubHubbub (PuSH) in Google Reader. With PubSubHubbub, new posts show up nearly instantly in Google Reader instead of up to a half hour delay. This means content gets pushed to your readers faster.

However, this will only work for sites that have PubSubHubbub enabled. Fortunately, this is very easy on WordPress:

• Install the PubSubHubbub plugin – you can do this by going to Plugins -> Add New and searching for PubSubHubbub. Two plugins exist, the one called “PubSubHubbub” seems to be the more popular and actively maintained plugin, so go with that one.
• Once its installed, activate it:
  
• Thats it. Your posts should now show up in Google Reader nearly instantly.