This module provides a block that displays the "open hours" of a facility, and the administrative interface for specifying those hours. To use this module, download the tarball (appropriate for your branch of Drupal), unpack the module to the appropriate modules directory, set the operating hours at admin/settings/hours, then enable the Today's Hours block at admin/build/block.
The D6 branch is a little more "feature-rich" than the D5 branch, and development of new features will occur more rapidly on the D6 branch.
This project ultimately will be posted on Drupal.org.
Please leave any bug reports, feature requests, and/or general feedback in the comments of this post.