It's capable, but needs suitable marketing for new arenas such as for business information systems
Inter-operability is key. It's a fact of life that most businesses have several different systems. Rather than carpet over all of them, Drupal should inter-operate, e.g. with SAP, Sharepoint, etc.
Drupal has many strengths applicable to business situations:
- tagging/taxonomy/synonyms to identify content. Content can have multiple tags, information becomes self organising, rather than being placed in rigid hierachical folder systems that get eroded by re-organisations,marketing names for products versus internal-code names for products.
- precise user permissions management to access and modify content
- clean meaningful URLs without .aspx, .php? etc in sight
As for Joomla and Wordpress, great alternatives but Drupal is a superset of all of them, its disadvantage being that these are already well established in their areas of strength and they are optimised to be easier to set up for those areas.