The local (regional) Motorola Type II trunking system here recently turned encryption on for all police talkgroups. Fire, EMS, interoperability and regionwide talkgroups remain in the clear. All local public safety is on the trunked system with UHF-FM analog backup for EMS and VHF-FM analog backup for hospital-to-EMS and other interoperability concerns.
The reason given for encrypting all law enforcement was that a task force busted somebody who was using a smartphone "police scanner app" (read: he was streaming the audio from somebody else's scanner, available from a well-known police scanner audio streaming site). Made the local radio folks here pretty angry as the city I live in produced some of the most fascinating police radio chatter I've ever heard.
The tactical or "talkaround"talkgroups (of which there are several dozen for the city police department) were unencrypted and the SWAT, narcotics and vice guys used them as their very own "party lines" or chat rooms - some racist, sexist, extremely offensive and also extremely funny stuff was heard. One could often hear the dispatch talkgroup chatter in the background of these conversations, making it clear that officers would have their car radio on the dispatch channel and their handheld radio on the "talkaround" channel. Going by how candid the cops were before their communications were encrypted...I wonder how much more is being said now that its encrypted.
TheRelayStation is right about heavy MDT usage too. There's also a "chat" or instant-message function available on the MDTs used by local police and state police here. State Police use a Project 25 digital trunking system and only the narcotics and other special talkgroups are encrypted. Compare that to the state game wardens, who are 100% encrypted.
The state law enforcement agencies here all operate on the statewide VHF Project 25 trunking system but maintain backward-compatibility on 39.540 MHz VHF lowband (analog FM) for communications with local sheriff's offices in rural areas, for car-to-car backup and as a statewide overlay/backup system for dispatch-to-car usage. When the state upgraded to Project 25 digital trunking they also upgraded the 39 MHz system and they've made it clear they only have plans to maintain/continue to upgrade that system. Many local agencies maintain patches on their respective trunking systems to the 39.540 MHz channel. All state police vehicles have a lowband radio that sits on 39.54 in addition to their primary digital VHF radio and MDT. Best of both worlds, I'd say.