There are a lot of theories flying around about why Twitter and other social media services got knocked offline yesterday. I ve heard rumors about it being linked to political tension between Georgia and Russia. There is no real data to prove who is behind it, and if there would be any clue about the origins of this attack, it would be in the access logs on the victim servers. Blaming the DDoS attacks on Russia, Georgia or Iran is always going to make the story more popular. The only thing that will happen is that Twitter will be even more popular after this.
Source: https://threatpost.com/cutting-through-twitter-ddos-hype-080709/73668/