Integration of the Facebook friends and the PSN friends would be a terrific start. Discover which of your facebook friends is on PSN and have that information linked to the PSN list.
XBL has a similar feature and I discovered the GamerTag of a bunch of people I didn't even know had them. I imported them into XBL with ease.
Perhaps an FB online status indicator under the PSN friend's details, etc. If you have a person on both PSN and Facebook, perhaps have their real-life name shown under their PSN name in the list. I confess I don't remember who a lot of these people are when looking at my PSN/XBL lists.
I hate, hate, hate messy/spammy walls/feeds..the signal to noise ratio is getting worse every day on Facebook and stuff like what's coming in 3.10 is useless. Sony is clearly viewing Facebook on the PS3 as a way to advertise (spam about the PS3 on people's walls) rather than connect gamers.