In response to a user request, I have added a second optional parameter to the calendar macro. It now takes two optional arguments, file and start-day. file defaults to the current weblog story file. You will rarely if ever need to specify it. Use nil to get the default. start-day is the day of the week for the first column of the calendar. 0 is Sunday, 1 is Monday, ..., 6 is Saturday. The default is 0, Sunday. Hence to put in a calendar starting on Monday, you would place the following in one of your template files:
\{calendar nil 1}