A company that some college students started in a dorm room eight years ago is now the world's most valuable brand -- for now.

Facebook was the world's most valuable brand in the third quarter of 2012, beating rivals Apple and Google, according to a new report from the research firm General Sentiment. Facebook was added to the ranking that quarter, and shot straight to the top.

The study quantified the value of big brands' exposure by analyzing "the sentiment, frequency and exposure of news mentions and social dialogue," it said.

But Facebook's place at the top may not last. Much of the media attention surrounding the company is the result of its disastrous initial public offering in May. And its brand exposure is on the decline, while number-two Apple's brand exposure is growing, according to General Sentiment's report.

Check out the world's most valuable brands below:

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  • 10. Yahoo

    <strong>Total value:</strong> $117,486,811 <strong>Value from news media:</strong> $38,012,185 <strong>Value from social media:</strong> $36,499,066 <strong>Value from Twitter:</strong> $42, 975,560

  • 9. Disney

    <strong>Total value:</strong> $120,241,613 <strong>Value from news media:</strong> $25,102,262 <strong>Value from social media:</strong> $20,673, <strong>Value from Twitter:</strong> $74,465,790

  • 8. Hewlett-Packard

    <strong>Total value:</strong> $131,908,932 <strong>Value from news media:</strong> $17,674,736 <strong>Value from social media:</strong> $88,725,016 <strong>Value from Twitter:</strong> $25,509,180

  • 7. Microsoft

    <strong>Total value:</strong> $240,836,396 <strong>Value from news media:</strong> $55,110,141 <strong>Value from social media:</strong> $141,800,955 <strong>Value from Twitter:</strong> $43,925,300

  • 6. Samsung

    <strong>Total value:</strong> $249,959,237 <strong>Value from news media:</strong> $59,922,215 <strong>Value from social media:</strong> $113,691,082 <strong>Value from Twitter:</strong> $76,345,940

  • 5. Amazon.com

    <strong>Total value:</strong> $258,013,554 <strong>Value from news media:</strong> $59,692,956 <strong>Value from social media:</strong> $97,192,968 <strong>Value from Twitter:</strong> $101,127,630

  • 4. MTV

    <strong>Total value:</strong> $536,020,286 <strong>Value from news media:</strong> $10,661,701 <strong>Value from social media:</strong> $6,337,955 <strong>Value from Twitter:</strong> $519,020,630

  • 3. Google

    <strong>Total value:</strong> $547,320,580 <strong>Value from news media:</strong> $147,724,920 <strong>Value from social media:</strong> $212,685,760 <strong>Value from Twitter:</strong> $186,909,900

  • 2. Apple

    <strong>Total value:</strong> $657,194,919 <strong>Value from news media:</strong> $228,358,036 <strong>Value from social media:</strong> $233,111,783 <strong>Value from Twitter:</strong> $195,725,100

  • 1. Facebook

    <strong>Total value:</strong> $751,163,560 <strong>Value from news media:</strong> $168,204,318 <strong>Value from social media:</strong> $150,074,462 <strong>Value from Twitter:</strong> $432,884,780