This feature was added to the master branch of QGIS about 4 months ago, but only for PostgreSQL/PostGIS databases, not Spatialite. The series of commits could be squashed down to provide a concise view of how to add such support for Spatialite. Please submit a feature request, and link to this page.
Interesting side note, Spatialite 4.1+ offers a new storage blob, XmlBlob. There has been talk of making Spatialite the default vector format (not shapefile) for QGIS. And, there is talk/plans for allowing many aspects of a project to be stored in a database, including the .qgs file, metadata and styles (I believe @nathan-w may be working on this). This is the reason the File menu was recently renamed to Project, since a database connection could be the sole source of a project.
The new XmlBlob offers a nice solution for these geo resources, and I for one, would like to see a simple solution for storing whole projects, with data, metadata, styles and symbols in a single, multi-platform db file (i.e. Spatialite):