Ah, you beat me to it! I was gonna post this earlier but forgot.
Very good move
Hopefully won't be too long before Sony add Trophies etc., & it will finally compare to the XBL Gamercard more.
Portable IDs have actually been available for a good few months now, but only if you signed up to the official US forums (PlayStation Underground) & linked your PSN ID to your forum account there.
These new ones are nicer though
US:
UK/EU:
There's a lot more to it too than just Portable IDs... they've finally done away with the various logins on the US & UK/EU sites, & made it so that you only use your PSN ID to sign in.
No more separate forum login for PlayStation Underground - PSN ID does everything on the US site now.
No more separate login for the main UK/EU site, while using the PSN ID for the forums - PSN ID does everything now.
You can also check your Friend List on the official UK/EU site now - very handy. Hopefully they'll add the ability to send messages via the website.
[You could check your Friend List on the web a while back by using a PlayStation Underground account on the US site linked to your PSN ID, as with the US Portable IDs. The new way is simpler though, & looks better.]