While we wait for ressources to become available for developing proper sync for mobile devices (e.g. Funambol), I've discovered sort of a poor mans sync for Android calendar:
1. From Android market find and install "iCal Import/Export" and run it.
2. In "Choose calendar to edit:" select calendar you want to import entries into
2. Click 'Set URL' button and insert your Feng Calendar feed
3. Click "Load iCal file" button. If it goes well, amount of found events will be displayed.
4. Press "Insert entries" to insert them into the calendar.
This will actually insert into the corresponding google calendar you selected, and subsequently kick through on your Android device.
NOTE! Only tested with fairly few calendar entries (250). Use at your own risk, and consider that a huge amount of entries could be inserted into your calendar, which could be hard to revert (fortunately app has button Delete entries based on the feng feed, so you should be able to reverse it).
Tested on Desire HD (Froyo). Feng 1.7.2