I'd like to see a party chat feature like on the 360, so all your friends can join a single party for cross game voice chat. The store needs to have actual PS One classics such as Gran Turismo, Tekken, Resident Evil etc instead of Hercules and Tarzan which is the kind of crap that Sony are giving us at the moment. Also, the Pal versions do not need to be inferior to the US and Japanese versions, just put a bit more effort in please Sony. At the moment we wait longer than the US and Japan and when we finally get the product it's usually inferior to the North American / Asian version, Final Fantasy 9 for a recent example.
On the subject I want to see PS2 classics put onto the PS Store as well, I'd love to be able to play the GTA series, Gran Turismo series, Resident Evil 4 and the Metal Gear Solid series on my PS3, I don't see any reason as to why Sony can't put those games up on the store, I'm sure they would certainly sell like hot cakes and I don't see Polyphony or Rockstar saying no.
Apart from that I think the system is fine as it is. I hear the XMB is having a full on refresh sometime in the near future, which is nice as long as they keep the ability to add your own themes or an option to revert to the XMB that we currently have.