Twitter jumps onboard the transparency train and has published details on user information requests by governments, requests to delete content, and DMCA takedown notices from copyright holders. You can view the report at Twitter's blog.
While Twitter explicitly stated that the data in the report is not 100% accurate, the data sheds revealing light on the global trends for removal and information requests. The company received more government requests from January 1, 2012 through June 30, 2012 (the span of this first report) than in the entirety of 2011. According to the report data, Twitter did not comply with any removal requests from governments. However, 63% of user information requests from governments were complied with, with the United States leading the number of requests at 679.
Another observation is that, at least for now, copyright takedown notices far exceed user information requests and content removal requests from government entities.