I found the following link:

http://maemo.org/development/sources/

Under the maemo 4.0 sources, there is source for osso-rss-feed-reader. I'm not yet advanced enough to try to build it, but there appears to be source code available for it there.

Once I figure out how to navigate the scratchbox I created, I will attempt it.

I could not find ossofilemanager or the mediaplayer, as you suggested.