Windows XP support will end on April 8 2014. This means that the total support will come to an end, not just the extended phase which it is in as of now. So no more technical support, security updates or service packs / hotfixes will be provided for XP after the cut off date. Complete list of support cycle for XP can be found here.
It is still a couple of years away yet this should be a strong and scary reason for many (especially corporates or institutions) to upgrade to Windows 7 considering that the market share of Windows XP among other Windows OSes is still around 43%. On top of it, many firms that run custom applications are only compatible with XP since they were deployed almost a decade back and upgrading them could possibly mean a total overhaul of Windows infrastructure but they would have no other choice once the support for XP is over.
For home users who still rely on Windows XP to do basic tasks like word processing, check emails and surf the internet, having no further XP updates or patches would mean being open to vulnerabilities. Fear not since options for avoiding this can include buying new hardware (dated hardware running XP would not guarantee a successful upgrade to Windows 7) or switch to Linux distributions like Ubuntu or Linux Mint. Both of these are free, easy to use, run well on old hardware and secure as well as adequate for normal basic uses.
Either way, this should be one interesting and hopefully smooth transition when saying goodbye to Windows XP in 2014.