This could potentially be quite big for Ubuntu and Linux in general. Canonical and the Chinese government have announced a collaboration to build a version of Ubuntu specifically for the Chinese market, which will become the reference architecture for standard operating systems in the country.
The first version will be released next month, and will be named Ubuntu Kylin. This first, initial version will already contain a number of China-specific tweaks, such as Chinese input methods and the Chinese calendar, and search support for the most popular Chinese music services will be built straight into the Dash, Ubuntu's global search thing. Future releases will expand to include integration with Baidu maps, the Taobao shopping service, Chinese payment processors, and local public transport information. The collaboration will move past desktops in the future.
"The release of Ubuntu Kylin brings the Chinese open source community into the global Ubuntu community," according to Mark Shuttleworth, "With Ubuntu Kylin, China now has its own secure and stable desktop operating system, produced alongside Ubuntu's global community. Ubuntu combines proven technology with a mature ecosystem and strong OEM and ISV partners, and this initiative allows the Joint Lab to bring those strengths to China across the full range of platforms: desktop, server, cloud, tablet and phone." 
The pros are pretty obvious, those being the Billions of new Linux Ubuntu users will be added to the Ubuntu community and the Kylin customisation will focus on security as well as stability.
The cons are not as obvious, those being Western State sponsored maleware, virus's and worms are almost certainly going to be created to target Chinese servers just as the same bad actors did the same to create Stuxnet, Duqu, Flame Virus's to target Microsoft OS inside Iran which have since been globally spread to Win-X users. Sadly, Linux distro's allegedly hadn't been the target of State sponsored maleware before and the vast majority of Linux users do not run rootkit checkers nor any antivirus application to make certain their system is as clean and secure as possible. This will likely change over the next few years as China fully embraces the Ubuntu Kylin OS and Western State agencys responds programming various keyloggers, virus and worms that specifically target the Linux Ubuntu OS which are bound to get into the global wild just as Stuxnet, Duqu and Flame virus's that targeted Win-x OS did from Iran to the rest of the world. 
 Ubuntu Kylin to become the Standard Operating System for all of China http://www.osnews.com/story/26885/Ubuntu_to_become_standard_operating_system_for_China
 Clam AntiVirus http://www.clamav.net/lang/en/download/packages/packages-linux/
 ClamTk Virus Scanner, A GUI front-end for ClamAV http://clamtk.sourceforge.net/
 Linux Detecting/Checking Rootkits with Chkrootkit and rkhunter http://www.cyberciti.biz/faq/howto-check-linux-rootkist-with-detectors-software/
 Security Checker - Tiger https://taufanlubis.wordpress.com/2008/02/08/security-checker-tiger/
 20 Linux System Monitoring Tools Every SysAdmin Should Know http://www.cyberciti.biz/tips/top-linux-monitoring-tools.html