A few people in my Twitter feed are voicing objections to FBI tweet. And it sure seems bizarre. So I wondered, what is it about? A bit of googling suggested some answers. (Thread)
First, the FBI's tweet has a link, so I tried that. But the site is down, so that didn't work. (Too much traffic? Angry DDOS? I don't know.) downforeveryoneorjustme.com/edo.cjis.gov 
So I searched to find out what an "identity history summary check (IdHSC)" is. I came across this regulation, first enacted in 1973 and most recently amended in 1999, saying that the law lets people get access to their own arrest and conviction records.
fbi.gov/services/cjis/…
fbi.gov/services/cjis/…
Under the '73/'99 reg, you can get a copy of your "rap sheet" based on fingerprints the FBI has-- events, like arrests/convictions, when you would have been fingerprinted. To get that, you need to send them your name and fingerprints to ID you, and they send you matching records.
I gather, based on the text of the FBI's tweet, that the FBI jnow has gone electronic: Instead of having to mail physical fingerprints, you can now do the process electronically at the post office if you want your rap sheet under this '73/'99 regulation.
If I'm right, this isn't a major new program or strange development. They're just making it easier to get your rap sheet, under some pretty old regulations, if you want it. I realize Twitter still gets mad at that kind of thing, but I'm not sure it's that big a deal. /end
