Jacek Dukaj is great, but I don't know when he will be translated.
He mostly writes hard sci-fi with political and philosophical elements, often about transhumanism, but he also did weird philosophical alternative history book - "Lód" (Ice).
Actually, on a polish fantasy convention Polcon Dukaj told a story about the attempted translation of "Lód". Hea gathered a group of seven people, Polish to English translators, russophiles, cultural experts and what not. He said, that after two days they gave up after not being able to agree on the first page. The historical and cultural baggage this book carries is just too great to be even remotely translated into english, although he also mentioned that there is a steggering amount of pirate translations into russian.
Dukaj is amazing, his "Other Songs" ("Inne Pieśni" in polish) is one of the best books I've ever read. I really hope it gets translated to english so non-polish speakers can read it.
I strongly recommend the works of Jacek Dukaj. His "Black Oceans" is one of the most idea-dense science fiction book I have ever read. And eerily relevant to our times, especially wrt. HFT and proliferation of surveillance.
I've heard some good things about Metro 2033 by Gluhovskiy, a post-apocalyptic novel about survivors living in Moscow underground train system after the nuclear war in 2013, but haven't read it myself.
Metro 2033 is a good read, I've been reading the German translation, and this still had that specific 'Russian soul' in it which is hard to describe. I was shocked how bad Metro 2034 is though in comparison, and I am not sure whether it was just a very bad German translation or whether the original book was also 'soul-less'.
Unfortunately there not so many soviet and contemporary russian authors are translated. So besides already recommended Strugatskie borthers there almost nothing.
Try Sergei Lukyanenko (multiple spellings). Most of his works are not translated in English (German has many more), but at least the Night Watch and Day Watch are. They were both made into movies too, though the movies absolutely sucked comparing to the books.
I can recommend Kir Bulychov and his funny stories about Great Guslar (fictional city somewhere in USSR that was frequently visited by aliens). I'm not sure, however, if this has been translated to english.
http://en.wikipedia.org/wiki/Kir_Bulychov
I love Lem's work but that's the extent of my familiarity with Eastern Bloc sci-fi.