You heard right. That time has come for the PSN name to cease to exist, and all who play online must conform with the new "SEN" or live a life of no more online gaming or PS Store access.
The new update is live in Australia now, so I can only assume the update will be live everywhere else too.
The following is the list of new features stated before you update:
*"The internet browser has been improved.
Some websites that could not be displayed, including interactive websites, are now supported, and page layouts are now displayed with better accuracy.
*You can now set to obtain the correct date and time automatically when you sign in to the PlayStation Network.
If you do not need to set the correct time automatically, set [Settings] > [Date and Time Settings] > [Set Automatically] to [off]."
I may update the post with some images later if there are any massive changes. For now, update your PS3, and pay your respects to the old and somewhat faithful name that was the PSN.
Edit: A bit of an anticlimax, but everything looks the same. Browser is a little faster and better at displaying sites, but all up it just seems like a different number more than anything.