According to me expansion is unnecessary in the rapidly changing world . In order to survive you have to bring new things to attract users .Is google bringing NEW things? the answer is both YES and NO . The Web giants has extraordinary resources and can do whatever they want .

If for you a social networking site coming into a IPO is not a expansion of business then may be you are thinking that Microsoft is expanding their business in many areas by launching windows 8 after windows 7. lolzz
There are always exceptions and virgin is one of them,most of the companies have got failed when they tried to do so.
Managing IPO is a different thing then running a social networking site !!

Agent and Technologist

Expansion is critical to a business' survival. The entire reason for that is exactly what Agent said - we are living in a rapidly changing world. This means that a currently successful business may become obsolete from one day on another. On top of that, if a company is successful, cash flow in the business deteriorates, as big piles of cash are stacking up. Companies generally use this money to expand, and stabilise as a business, or in R&D.

Technologist:
I have no clue how you got the idea that floating on the stock market = expansion. In fact, I have an even lower comprehension on why you would say that Windows 7 to Windows 8 is "expansion", as it's releasing a new product. I advice you to read up on finance and business management, as you're sounding rather clueless.

Exceptions? Every major business went through significant expansions in its lifespan. Microsoft expanded into Video Games, Office Products and Hardware. Sony expanded into Film, Music, Software, Video Games, Hardware, MP3 Players, and much more. In fact, the only large company I can think of that hasn't expanded into other fields is Nintendo.

Walmart expanded, Gamestop expanded into publishing and flash game production, name any company and I'll tell you what they expanded into.

An IPO is a model of funding, and has absolutely nothing to do with the products they produce.

You are absolutely correct. Problem is spreading yourself too thin. google thinks that they are invincible. Problem is that they are not. They have lossed marketshare in their search and that is their bread and butter. Without that, they can't fund "other ventures". Yes while they dominate the search engine, they won't always dominate it. Now with the rapid net explosion and chinese ripoffs, you can't think that just name alone will sell.
Nintendo didn't take sony seriously while they dominated the gaming market. Well sony being a bigger company showed Nintedo up, didn't they. Same for google and their search engine. People will always find alternatives and that is a risk that google cannot afford at ANY cost. Without their ad and search, they're dead in the water. Stick with what you are good at. That goes for all companies including MS. droid is just an open source ripoff of ios. Nothing new...