20 years ago if you wanted a real-time stock quote you had to phone up your broker.
Then along came the internet and you could get real-time quotes for a fee from your broker's website or for free with a 15-20 minute delay on sites like Yahoo! Finance and money.cnn.com.
Now, Bats Trading, one of the larger ECN alternatives to the NYSE and Nasdaq has agreed to stream real-time quotes direct to Yahoo! Finance.
Gotta love competition in big markets like the US :)
Update: Now the Nasdaq have agreed to provide real-time quotes to Google Finance, the Wall Street Journal, CNBC and Xignite.