This is a simple script that dumps the groups, and optionally the weights, of selected vertices on a mesh. Its likely to only run on 2.34 without changes though, so grab a test build if you aren’t working with a CVS build already or wait until 2.34 is released.
The script can be found http://www.visi.com/~zaz/vertexGroups.py for download or for posterity in the code block below.
Since this is so trivial, it is released without restriction, do with it as you wish.
#!BPY """ Name: 'Selected Vertex Group Dump' Blender: 234 Group: 'Mesh' Submenu: 'Vertex Groups Only' onlyGroups Submenu: 'Vertex Groups With Weights' withWeights Tip: 'Print Vertex Groups for Selected Vertices' """ import os import Blender from Blender import Object, NMesh if __name__ == "__main__": editMode = Blender.Window.EditMode () if editMode: Blender.Window.EditMode (0) Blender.Redraw () Blender.Window.EditMode (1) obj = Object.GetSelected ()  mesh = obj.data groupCount = 0 count = 0 onlyGroups = __script__['arg'] == 'onlyGroups' print "Selected Vertex Group Dump, processing mesh", mesh.name, "from object", obj.getName () if onlyGroups: for grp in mesh.getVertGroupNames (): groupCount += 1 for vidx in mesh.getVertsFromGroup (grp): vert = mesh.verts [vidx] if vert.sel: count += 1 print " ", grp break print count, "groups involved out of", groupCount, "total groups." else: for vert in mesh.verts: if vert.sel: print " Vertex:", vert.index, vert.co glist = mesh.getVertexInfluences(vert.index) if len (glist) > 0: for inf in glist: print " ", inf , inf  else: print " **NO GROUPS**"