Beginning today, is one of the biggest court cases in tech history. Oracle are suing Google to the tune of $1 billion, where they're claiming that Google have violated several patents and copyrights. What the fight is over exactly, is due to Oracle acquiring the intellectual properties of Java when they took over Sun Microsystems back in 2009.
Oracle are claiming that Google's mobile OS, Android, infringes on several of its IP rights relating to the program language. Java was released in 1995, and allows software to run on multiple computer platforms, instead of just one type of operating system. Oracle argues that by using their IP (Java), and then giving Android away for free, Google are undermining the possibility of licensing Java to mobile phone makers.
This doesn't mean the end of Android by any means, but what it does mean is we could see a big change in Android in the near future. If Oracle ends up winning, they could force Google to change their Android code, which would make millions of apps for Android, useless. Alternatively, Oracle could force Google to charge for development of apps.