They are not letting them congregate downtown anymore. They closed the Union Gospel mission downtown because it was becoming a big drag on local businesses for a few blocks around that (which Salem really is just a few blocks anyway for all of the downtown business core). The homeless would hang out on most city streets during the daytime, was a big deterrence for foot traffic downtown, business owners were complaining. they also built a large new police station right next to downtown which has probably pushed many of the homeless away, especially ones that maybe were causing more of a disruption through vandalism, drugs, etc.
They have been on a huge building spree around the city on high density, apartment and affordable housing, so I think it's helped some of the ones who's minds aren't ruined by drugs or that don't want to be housed, find options.
Across the river though in west salem is one of the country's largest homeless encampments, throughout Wallace Marine park, an extensive wooded environment near the river. They're ruining the ecosystem over there though from what I've heard.
Oregon in general has got to lead the country in lack of options for those homeless, addicted or mentally ill. It's very sad.