????2011年是Facebook公司歷史上的一個好年頭。這個社交網絡以每幾個月就增加1億用戶的速度持續增長。盡管股市大環境頗不景氣，其首次公開募股（IPO）依然穩步邁向高達1,000億美元的市值。而最引人關注的是，它已經讓主要競爭對手谷歌（Google）疲于奔命。

????Facebook已將谷歌的一流工程師招至旗下，對谷歌的廣告收益也虎視眈眈。更重要的是，Facebook迫使谷歌重新設計網頁，以顯得更社交化，更“Facebook化”。要想知道你是不是在搶對手的飯碗，最明顯的標志就是看看他們是不是在模仿你。

????顯然，2012年對Facebook就要殘酷得多。美國市場的用戶數量止步不前，廣告收益也不如人意。從某項指標上看，它的首次公開募股甚至稱得上華爾街史上最差。上周，Facebook首席執行官馬克?扎克伯格表示，公司可能會引進搜索引擎來創收。

????這簡直就像硅谷版的《怪誕星期五》（Freaky Friday）：白發蒼蒼的網絡巨人和傲慢自大的網絡新貴彼此交換了角色。社交網絡用戶增長1億的是谷歌，市面蕭條的變成了Facebook。（它的市值為480億美元，僅相當于谷歌的五分之一。）兩家公司甚至連言論都開始向對方看齊。拉里?佩奇把谷歌稱作“社交的歸宿”；扎克伯格則說：“搜索引擎正朝著給用戶提供一系列答案的方向發展。比如，我有一個問題，引擎能幫我找到答案。”

????為什么會這樣呢？一個原因是，兩個競爭對手不可避免地要向對方的領域發展，甚至模仿對方。要想進一步了解這一方面的問題，不妨關注一下智能手機行業司空見慣的專利訴訟。【此外，據《財富》雜志（Fortune）2011年封面故事報道，兩家公司的專利之爭由來已久。】

????更重要的是，不論搜索引擎，抑或社交網絡，本身都不是上佳的商業模式。人們蜂擁而至，使用Facebook和Twitter只是因為這類網站是通過朋友和聯系人發掘新鮮娛樂方式的一個好去處。這種情況并不會讓搜索引擎失去人氣，只是讓人們從網絡上獲取的內容變得更加豐富多彩。所以，谷歌和Facebook會不可避免地插手對方的核心業務。

????有人認為，搜索時代已經過去，網絡的未來將屬于社交網站，實際上這種觀點也開始過時了。的確，比起搜索框，社交網絡也許更能吸引人們流連忘返。不過他們點擊那些惱人的廣告所耗的時間也大大減少了。我們會去社交網絡結識朋友，去搜索引擎尋找答案。所以盡管搜索行業即將滅亡的警告不時可見，但搜索廣告依然表現良好。

????鑒于兩家公司之間凸顯的競爭關系，Facebook想要進一步打入搜索行業的計劃看起來就像是遞交了一份尷尬的投降書。不過就像佩奇決心發展社交網絡以強化谷歌的全方位服務一樣，扎克伯格將搜索當作促進Facebook未來發展的一個收入來源。考慮到Facebook迄今為止乏善可陳的股市表現，這個想法看起來不錯。

????加入搜索引擎，這并不是Facebook模仿傳統網絡廣告的唯一舉措。幾個月前，Facebook的廣告競價系統（Facebook Exchange）上線，允許廣告網絡使用用戶的瀏覽歷史記錄，借以定制用戶喜好的展示廣告，放置在Facebook的新聞旁邊。Facebook的廣告競價系統的工作機制酷似谷歌的廣告交易平臺（Google's Ad Exchange），在它的測試程序中，我們能看到增加廣告點擊率的蛛絲馬跡。

????Facebook和谷歌在其他一些領域也存在競爭。比如Facebook的相冊（Facebook Photos）和谷歌的圖片管理工具（Picasa），Facebook的Facebook Messaging和谷歌的GTalk。此外，兩家公司都在網絡廣告方面大量使用古老的方式——歷史悠久的展示廣告，這是將近20年前的東西了。

????2011 was a good year for Facebook. The social network was adding 100 million users every few months. It was on track for an IPO valued as high as $100 billion -- despite a dispirited stock market. And, perhaps most impressively, it had its archrival Google on the run.

????Facebook (FB) was hiring Google's (GOOG) top engineers and threatening to siphon off its ad revenue. Significantly, Facebook was forcing Google to redesign its sites to be more social -- that is, more Facebook-like. There is no clearer sign you're eating your rival's lunch than the sight of them emulating you.

????Of course, 2012 has been far crueller to Facebook. User growth stalled in its home market, and revenue growth disappointed as well. Its IPO was, by one measure, the biggest flop in Wall Street history. And last week, Facebook CEO Mark Zuckerberg indicated that the company might introduce a search engine to drive new revenue.

????It's Silicon Valley's version of Freaky Friday: the aging web giant with touches of grey and the cocky upstart have reversed roles. The company adding 100 million users to its social network is Google. The company with the sagging market cap is Facebook. (Its $48 billion valuation is a fifth of Google's.) Both companies have even started to talk like each other. Larry Page describes Google as "a social destination" and Zuckerberg says things like, "Search engines are really evolving towards giving you a set of answers… like, I have a specific question, answer this question for me."

????What gives? One answer is that corporate rivals inevitably bloat their ways into each other's turf, even to the point of copying each other. For a clear illustration of this, look no further than the patent lawsuits that have become a staple of the smartphone industry. (Plus, as Fortunechronicled in its 2011 cover story, the battle has been a long time coming.)

????More importantly, neither search nor social networking is an inherently superior business model. People flocked to social sites like Facebook and Twitter because they were a great way to discover new diversions through their friends and contacts. But it didn't make search less popular. It just added to the flow of content people get from the web. So it was inevitable that Google and Facebook would move into each other's core businesses.

????In fact, the notion that search was dying and that the future of the web lay in social networks is itself starting to look outdated. Yes, people may spend many more hours on a social network than in a search box, but they also spend much less time bothering to click ads. We go to social networks to find people. We go to search boxes to find answers. So search ads -- despite warnings of the demise of search -- have continued to do very well.

????In light of the rivalry that has emerged between the two companies, Facebook's plans to push harder into search may appear like an embarrassing capitulation. But just as Page was intent on moving into social to strengthen its overall offerings, Zuckerberg sees search as one more revenue stream to feed into its future growth. And given Facebook's lackluster stock performance so far, it seems not a bad.

????Nor would adding a search engine be the only move that Facebook has copied from traditional web advertising. Several months ago, Facebook Exchange launched, letting ad networks use the browsing histories of users to target display ads next to their Facebook news feeds. Facebook Exchange, which works a lot like Google's Ad Exchange, showed early signs of improving ad-click rates in its beta program.

????Facebook and Google also compete in several other areas, with Facebook Photos taking on Google's Picasa and Facebook Messaging aping GTalk. And both have made heavy moves into an even more archaic form of web advertising -- the hoary old display ad, introduced nearly two decades ago.