Using a service like BTJunkie is not, and never has been, illegal. But as we saw with the recent Megaupload takedown, the entertainment industry - often aided by surprisingly zealous governments - tends to cast a very wide net when trawling for such sites. We seem to be moving into a situation where sites that could be used for sharing copyrighted material are being targeted despite the fact that most of their users use them for wholly legitimate purposes.
The Megaupload case seems to have had a real impact. As well as BTJunkie, sites like Quicksilverscreen have also ceased to operate. The drive to hold website owners accountable for every single action by their users seems to be taking hold and so far, 2012 looks to be one of a series of successes for the mainstream entertainment industry. It remains to be seen whether that trend continues.