It doesn't help.
Russian criminals have some of the biggest botnets (multiple gbit/s downlink) that can even bring down sites like Twitter & Facebook at the same time.http://www.pcworld.com/article/169809/twitter_ddos_attack_politically_motivated_says_report.html
Note that Facebook used some of the highest bandwidth servers in the world during the attack.
It still doesn't help even with attack patterning.
A site such as Mt. Gox has no chance to survive even if an attack with just a fraction of that, or 5-10k connections TCP flood it.
Most small to medium sized companies will pay protection money to stop the attacks coming because they lose more in business daily than they would pay the attacker.
The problem is that this opens you up for frequent extortion because you already paid once.
I don't think Mark considered the option of paying $7000 as requested earlier.
Well in that case maybe TORing mtgox.com is the solution.