The Real Threat to Google
(Yahoo! Singapore - Finance)

Google's biggest threat may not be Microsoft (MSFT) or Yahoo! (YHOO).

No, one of the most formidable challenges facing Google (GOOG) is likely sitting in your pocket or purse. It's your cell phone, and it will put added pressure on Google and other Internet companies to revamp the way they handle online marketing.

As more people use cell phones and their tiny glass screens to gain access to the Internet, Google and its fellow online advertisers will have less space, or what's called ad inventory, to place marketing messages for customers. Google makes money selling ad inventory. And its ad inventory is diminished on a cell phone.