Apparently publishers are putting out calls for submissions. These calls are also being passed around the social networks. Perhaps you see these calls if you are following the publishers on your favourite social network. However, over at Call My Agent one commenter mentions that some of these calls actually involve a fee. So, as ever, look out for traps.
While it means that the publishers must have to wade through a huge slushpile, some of them do sometimes decide to do this. Black Library, for instance, which publishers fiction based on the Warhammer game, has an annual open submissions season during April. They are not, however, accepting submissions for novels from new writers in 2012. 2000 submissions in three months is too much even for them. However, you can still try your short stories on them. More info here.
It's good to know there are opportunities out there. We just have to find them.