Apart from the geomap widget, jQuery Geo comes bundled with functions to perform various operations on bounding boxes (a.k.a, bbox, the rectangle surrounding any geometry) and the geometries themselves. These functions (and two objects: WKT & proj) are all contained in the $.geo namespace.
Geometry isn't much fun if you can't do anything with it. These functions help you analyze and manipulate bounding boxes and GeoJSON geometry objects. You call them directly from the $.geo namespace, e.g.,:
$.geo.distance( point1, point2 )
Except for a few name changes and switching from an object-oriented API to a function-based one, jQuery Geo attempts to follow the names and behavior of the Java Topology Suite (JTS), which is the de-facto standard for geometry library APIs. JTS itself is an implementation of the OGC Simple Features specification but has made design decisions that improve the API for developers. The most notable of which is having Envelope (called bbox in jQuery Geo and GeoJSON) be its own class type.
These functions operate on GeoJSON geometry objects: Point, LineString, Polygon, MultiPoint, MultiLineString, MultiPolygon, and GeometryCollection. They do not operate on Feature or FeatureCollection objects, you have to call these functions on the geometry properties of Feature objects.
The geometry functions allow you to analyze relationships between geometries such as their distance apart as well as obtain information about them such as bounding box and center point, called the centroid. This section will eventually expand to cover all of the important spatial operations available in the Java Topology Suite.
Please note the difference in case between the two objects on the $.geo namespace. $.geo.WKT is all upper-case because it is static and patterened after the HTML5 global object named JSON, while $.geo.proj can be modified and is closer in concept to an instance property of an Object type, e.g., how the jQuery $.callbacks object is an instance of the Callbacks type.