Yes. In the simplest case, this depends on how well you can define the categories. If you can specify a query or set of words describing each category, it is quite straightforward. Assigning a category does not need to be a yes-or-no operation; multiple categories may be assigned with a strength (relevance) rating. In many cases that we see, the source or author of a document, or other metadata, plays a significant part in the rules determining category assignments.
In other situations, the rules for assigning categories are not so clear cut. Categories may have been assigned in the past by humans who simply "know one when they see it." For these needs, the Texis Categorizer is available as an add-on module. The Categorizer "learns" to reproduce these decisions from past the category assignments. It assigns the most likely categories, each with a relevance score. New categories may be created by administrators on an ad-hoc basis.