The memory consumption thing has been taken by the Xbots and twisted (as usual). The same Xbots also imply the blade system on 360 uses no memory!!! (that would be impressive...)
On PS3, the memory is only used when the features are used, and the modules memory useage is not constant. Trying to claim that if you want X Feature, you will permemantly loose Y MB in your game is total nonsense.
Think of how a game uses these features. For example, ingame invites. You don't invite a friend to a game DURING gameplay (unless it's a strategy game perhaps), it's either during loading, before you launch the game, or in the pause menu. Once the invite has been sent, you return to the gameplay. The invites module code is unloaded from memory, from that point, it uses notifications "XXX has accepted" for example.
Very few of these features actually consume memory permenatly. They malloc it when you configure them, and then unload most if not all of the memory/funtionality when you return to the game
Another example Ingame music, will consume memory when selecting tracks/playlists, but once the music is playing, and you have returned to the game, the memory used drops to a very minimal subset of the modules memory useage and is used simply to play the stuff. Most modules use the majority of their memory whilst configuring whatever functionality they provide.
The obvious exception, is the PSP remote display, which uses the same amount of mem regardless, as it's running overhead is the main part of it's useage (8MB)