The Bureau of Justice Statistics is out with its report on rates of sexual abuse in jail and prison, which shows an "estimated 4.4% of prison inmates and 3.1% of jail inmates reported experiencing one or more incidents of sexual victimization by another inmate or facility staff in the past 12 months or since admission to the facility, if less than 12 months." I tend to think these numbers are probably low given the incentives that the incarcerated have -- revenge, social stigma -- to keep quiet. Women are more than twice as likely to be abused by other inmates than men.
In the meantime, the Department of Justice still hasn't released its standards for prevention of sexual abuse during incarceration, despite it being several months past the June deadline for doing so. When the standards are finally released, facilities that fail to comply could lose their funding.