From my notes:
Which parses like this:
q=latN+lonW+(label) location of teardrop
t=k keyhole (satelite map)
t=h hybrid
ll=lat,-lon center of map
spn=w.w,h.h span of map, degrees
iwloc has something to do with the info window. hl is obviously language.
See also: http://www.seomoz.org/ugc/everything-you-never-wanted-to-know-about-google-maps-parameters