SubText 1.9.4 has added support for displaying the category list for your posts. By default this is not included in your skin, adding new functionality to your layouts without your permission is obviously bad (and the control adds a couple of new queries against the database, something you may want to test before rolling out). So you need to update your skins (and this generally includes the default skins included with the software) to include the new control, should you want it.
In order to enable this you need to edit 3 files in your skin controls directory ;
Firstly you need to copy PostCategoryList.ascx into your controls directory and edit the template to match the format you want the category list to appear as. A suitable ascx is include in the "naked" skin; you can find this in your subtext installation in the \Skins\Naked\Controls directory.
Next you need to edit the files listed above and add a new tag registration;
Finally add the new control declaration;
wherever you want the category list to appear.