pagesetup event not firing in elgg 2.1?

i am part way through upgrading my site to 2.1 and am testing the version of 'river_addon' that is available on the elggzone website for 2.x.

i'm sure at some point i saw it all working ok, but presently there are no widgets rendering in the sidebars on the activity page and when debugging this i found that it appears that the pagesetup even is not working correctly. the event handler is defined:

    elgg_register_event_handler('pagesetup', 'system', 'river_addon_pagesetup', 1000);

and if i put any kind of error_log or elgg_dump command in there i get no result from it. is the pagesetup event still functional in elgg 2.1?