I see a lot of this on my google app engine error log:
05-18 06:44AM 00.897 /NTp9 405 17ms 0cpu_ms 0kb Twitterbot/0.1,gzip(gfe),gzip(gfe)
128.242.241.133 - - [18/May/2010:06:44:00 -0700] "HEAD /NTp9 HTTP/1.1" 405 124 - "Twitterbot/0.1,gzip(gfe),gzip(gfe)"
May I know what is this?