The one thing i find that PSN is missing is cross game chat, it's something we've all been waiting for and would really improve on the solid base the PSN already has. SKYPE would be a brilliant way to bring cross game chat to the PSN and would be even better than the current chat tools on services such as Xbox Live.
SKYPE would provide:
24 people confernce calls
Cross game cross platform chat
Abilty to call landlines and mobiles
All from your PS3, so sign if you really think SKYPE is the way forward for the PSN.