But they've tried to copy Xbox Live in some areas and are updating PSN in the next firmware to get even closer, so I don't agree that it's a strategic move. I also am not implying that Sony can't do it, just that in terms of work effort it's more than taking some open source instant messaging platform and dropping it on the system. And while Sony is building this other system that complements the online experience, Microsoft will be adding features and improving their own.
Sony will need an Xbox Live-story, one where match making is not done in 3d and I can see my friends without having to use some quirky interface. With the introduction of Home, I think Sony has committed themselves to building both this new 3d world and a simplified one that behaves much like Xbox Live's interface.
You might want to check out the GDC thread for a lot of these discussions (cuz it's tiring to repeat it here
and will derail this thread). Essentially...
You can access online gaming functionality (including Xbox-style achievements) from XMB itself. So you should be able to see your friends without having to use some quirky interface (XMB does that in limited form today, except that the list is not integrated in-games yet).
Online gaming functionality provided in PSN are enabling functions and basic features. The strategy part of PSN is to keep it open for third party to come in. In addition, the business planning and marketing behind Home is also a strategic move.
PSN may indeed be taking a Jabber like approach where a central platform interoperates with probably IM platforms (e.g., MSN, Yahoo IM and AOL). But in terms of work effort, they will need to come up with a more efficient implementation; the general idea may be not far off (We don't know for sure yet). XBL of course has deeper developer support today, more features like movie download and may be improved further e.g., spectator TV in the future, but ...
It's not clear what Sony's scope for PSN is today. They may attempt to leapfrog in 1 or 2 specific areas. The open platform approach typically takes more time to jump start. Time will tell.
And yes... "Sony has committed themselves to building both this new 3d world and a simplified one that behaves much like Xbox Live's interface" Depending on how Sony package the final experience, you may be able to jump between these 2 worlds seamlessly. The community aspect of Home is a lot deeper.