January 25th is known as Tatiana Day, also known as Russian Students Day. It is celebrated in Russia on January 25th, the Russian Orthodox Church declared Saint Tatiana the patron saint of students, and Tatiana Day has become celebrated as Russian Students Day.
Google planned on having a special Google Doodle on Google Russia for the day, but the logo never made it up.
Here is the logo:
It is a nice pretty logo!
Why didn't it go live on January 25th at Google Russia? The day before there were 35 people killed in Moscow airport. The attack was a suicide bombing allegedly by a terrorist group. You can read more about it over here. That is the reason Google withheld the logo.
Sometimes Google shows a sign of respect for sad days by putting up their black and white mourning Doodle. This time, Google withheld a happy logo.
Forum discussion at Google Blogoscoped Forums.