Technically, http://aspn.activestate.com/ASPN/Cookbook/Tcl is not a real book with ISBN, etc. It is however a community project to categorize Tcl solutions to various problems.
It's easy to speculate that ActiveState will want to render the book on dead trees when it becomes sufficiently successful.
It's a bit confusing as of September 2001 distinguishing the roles of this book, BOOK Programming Language Examples Alike Cookbook, this Wiki itself, and tcllib. Clarifying these relations over the coming months (days? years?) will be a considerable benefit to the community.
LV writes "In my mind, tcllib is the preferred location for Tcl code of general use, since by putting code in tcllib ensures that programmers who load that library automatically have use of the code, with updates, as they become available, etc.
No other method of publication allows that ease of use.
I can't tell whether there is an attribution mechanism there to indicate that code originally came, for instance, from this wiki or other sources.
On the wiki, one is vulnerable to anyone passing by and changing code - certainly one concern. One argument has been that some people have a tough time finding things in the wiki. Certainly we can categorize things here in manners similar to the ActiveState site. The one thing that ActiveState does provide is a salary to someone to refine the code there, etc. while the wiki depends on the kindness of strangers.
(2001-09-13) see BOOK Programming Language Examples Alike Cookbook for the position of Tcl-PLEAC.