Pubsub is a service that tracks your keywords for you. For example I wanted to see what people are talking about the Singapore economy. I can put this keyword on to Pubsub and track it continously. Pubsub will find articles with this keyword as they are published and bring them to you. You need to have a subscription to some feed reader or news reader tool to make full use of Pubsub.
Step 1: Here we are on the main page of pubsub. (www.pubsub.com). I enter “singapore economy” as my keyword. After typing in the keyword, I clicked on the “start matching” button.

Step 2: On the next page, Pubsub will ask you to select your feed reader.

If you are using Newsgator, My Yahoo or Bloglines, just click on those tabs. If not, just right click on the orange tabs on the right and copy the shortcut. Paste this shortcut in your feedreader.
pubsub vs technorati ? which is better ?
I am partial to Technorati, there is a lot more you can do with technorati.