There are obvious mitigating factors that make this easier. For example, attending the affair with one or more other people helps. (I think married folks have this easy -- they have a built in conversation partner, and someone who can tag-team with them in case of awkward gaps in conversations.)
Attending an event where you've had enough previous contact with the people to know a few names, faces, and hometowns also helps out. The more people you already know -- even slightly -- the easier it is to meet more folks.
But these factors don't help in situations where you are attending an event alone and know virtually no one. Conference organizers could help somewhat by taking this sort of thing into account -- for example, providing nametags that are very descriptive, or even providing a list of attendees and their backgrounds as part of the conference packet. Sometimes they do, but often you are cast adrift with no lifeboat.
From years of experience with this sort of thing, I have decided that I am simply lousy at this sort of spontaneously-generated "cocktail conversation." You'd think they would teach this sort of thing in school. Maybe they do, and I just skipped class that day. In any case, I think it's a skill I need to develop. Anyone know where I can find an online class?