People are commenting here without reading or understanding the ruling [edit: I should say that headlines like the one techdirt gave their article are also misleading; they are playing up the "banned from the internet" angle]. What happened is that North Carolina passed a law making it a crime for someone previously convicted of a sex crime to access social media sites (unless the site completely prohibits access except by adults, which most sites do not do). The court ruled that this law is unconstitutional on First Amendment grounds.
The court did not rule that "no one may be banned from the internet" an so on. A specific person can still have conditions attached by the courts to his release; for example, it's common for judges to impose conditions like "no use of computers" on convicted malicious hackers as part of their probation. This hasn't been made illegal. Restricting internet access of current prisoners certainly hasn't been held illegal. What's been held unconstitutional is criminalizing a priori certain modes of speech by a broad class of people.
EDIT2: Since this is apparently attracting a little bit of controversy, I want to add that I did not express any opinion about whether it's good to ban people from using computers or whatever; I just wanted to describe what the ruling says. I am actually not a fan of the general concept of not restoring people's rights after they serve their punishment, although I think it's justified in specific cases.