Spurred by Mark's message about cruft-free URLs, the Blosxom list has been full of discussion about how to do good permalinks in Blosxom. There's been some confusion; Blosxom has quite clean permalinks.
Blosxom supports two kind of permalinks: date based and file based.
Date-based permalinks look like this:
File-based permalinks look like this:
blosxom.cgi, with no flavour files installed, uses date-based links. So do the flavours in the Blosxom flavour sampler. Many of us, including the author of Blosxom, prefer file-based permalinks. The joy of Blosxom is either kind of permalink will work. By editing flavour files you can easily decide which style you serve.
Personally I think the date-styled permalinks are crazy and Blosxom's defaults should be file-based.