English term (edited): “workers out! 2nd world conference of lesbian and gay trade unionists”

Oh, go on, I can't resist having a stab myself! It means "out" as in "not hiding their homosexuality". Preliminary research indicates that in Russian, "открытость" and "открытый" are used for this:

"И так легко пойти дальше, в область моральных норм, приписывая такие качества, как храбрость и честность *"открытым"* геям и лесбиянкам, и трусость и даже предательство "закрытым"..."
http://www.lesbiru.com/comingout/privacy.html

"Идея проведения гей-парад вызвала гневную реакцию мусульманских и православных общин. Один из муфтиев призвал правоверных побивать *открытых* геев и лесбиянок камнями..."
http://news.bbc.co.uk/hi/russian/russia/newsid_4741000/47411...

(Plenty of other Googles if you look).

Since the term doesn't seem to be particularly widely used unless it's with "геи/геев" etc., though, you could perhaps put it in inverted commas. Only a tentative suggestion, though - there may well be another word for it which I haven't found!

I suspect there may be a play on words here with "out" - which might also mean that they want to get workers "out" to the conference in large numbers (i.e. mobilise/rally them), but how you could combine the two in Russian I really don't know. In any case, it may well not be a play on words!