In my code I've connected to the WebView's load-finished event. The particular callback function takes a webview object and frame object as arguments. Then I tried executing get_dom_document() on the frame & the webview objects respectively. It seems this method doesn't exist for those objects...
PS: i started with the tips i got here http://www.gnu.org/software/pythonwebkit/
UPDATE (11-Sep-2010): I think the link I shared relates to a new & different project. Its not a solution per se. My bad!