Informer

a usecase of that

busy user minding business
    phone rings
picks it up

busy user minding business
    sms arrives
picks it up

busy user minding business

    off-the-shelf
    news alert arrives
    job alert arrives
    stocks alert arrives
    events alert arrives
    deals alert arrives

    publisher-defined   
    bills alert arrives
    instant messages alert arrives
    email alert arrives
    bank account change  alert arrives
    orkut scrap alert arrives
    application down alert arrives
    weather alert arrives

    user-defined
    when a particular web-page changes.
picks it up

paradigm shift in the way internet is used-fire and forget
    user defines alert.
    when something interesting happens, system alerts user.
    pull based internet

integration with other alerting systems
build alert integration api

Technologies
android
blackberry
iphone
other mobile agents

Implementation:
Use a cloud based engine like google appengine so that scalability can be managed and it incurrs low startup costs.
Create a POC using a single technology-alert type and show that this system works.
Approach the customer directly by publishing the application in market,iTunes,.. and through loyalty, build a strong customer

base.

Revenue Model: Charge the alert content publisher/ and Advertisement based.