What happened to the "ghost prisoners"?

Thankfully not everyone has forgotten that they exist though it does not appear there are many answers as to what has happened to them, as evidenced by this Washington Post article, From CIA Jails, Inmates Fade Into Obscurity. It's not even clear how many of these prisoners exist, though the popular belief is there is around 30 of them.

Some have been secretly transferred to their home countries, where they remain in detention and out of public view, according to interviews in Pakistan and Europe with government officials, human rights groups and lawyers for the detainees. Others have disappeared without a trace and may or may not still be under CIA control.

I recommend reading the full article, groups like Human Rights Watch do have partial lists of those they believe are being secretly held, such as this one updated in 2005.

Then another article from the Post in 2005 that points out Keeping such "ghost" detainees is a violation of international law..