From the Twitter blog:
On Oshogatsu (Japanese New Year), Japan virtually shuts down as people spend the day with family and the people with whom they are closest. People make it a point to call their friends and connect with everyone they know to celebrate. With a population of over 127 million, Japanese mobile networks have been known to crash under the strain of this collective cheer. This year, on New Year’s Eve, many people turned to Twitter to celebrate.
The new record more than doubles the previous one of 3,283 TPS, set during Japan’s victory over Denmark in last summer’s World Cup. In fact, on New Year’s Eve, that all-time TPS record was shattered more than 68 separate times within a single 3-minute period.