Lightroom uses SQLite, an open source SQL database engine, for its library storage. However, the database schema are not documented publicly.
In principle, the use of an open source database should mean that other developers would be able to write tools that extraction information and report on the content of the library. In practice, the absence of documentation has meant that very little of that has happened.
LR does have a feature that causes the data for each image to be written to an XMP data packet for each image. If the image file is in a format that Adobe knows they can safely modify, the XMP data is written into the image file itself. If the image is not (a proprietary RAW file, for instance) then the XMP data is written to a sidecar file. XMP is a dialect of XML based on RDF and inspired by the IPTC Information Interchange Model and the Dublin Core Metadata Initiative.
Given that collection of XMP data, which is in a (mostly) documented format, it is likely to be possible to transform it to be easily imported into Aperture or another asset management system.