circos 0.52-2 released on September 21, 2010. Unfortunately I've not found a suitable changelog. Here are comments from 'Download' page: circos-0.52-2.tgz is a bug release. Replace contents of circos-0.52 with files from this archive. circos-0.52-1.tgz is a bug release. Replace contents of circos-0.52 with files from this archive. Reproducible: Always
Circos 0.55 released on July 26, 2011. ChangeLog included in tarball is too lengthy to quote it here.
Thanks for reporting. 0.55 does not have a Build.PL file so can't be automatically installed. I've sent a message to upstream, it will help if they fix it.
Fixed, please test