start-up effort in sentiment detection and analysis

"Semantic analysis" or "semantic measurement" or "sentiment detection" are very popular with startup's. Take for instance ScoutLabs and SkyGrid. The former capitalizes on the early warning detection of security-related events in news and the latter is watching negative and positive sentiment in news about business in order to inform stock market trends. In both occasions, the sentiment analysis technology relies heavily on automatically analyzing natural language input in unstructured form and filling records of a database with the extracted/tagged information. One has to wonder about the limitations of database systems for successfully undertaking such task.