I think I remember someone here talking about a revision of Ultramodern Firearms. Is that true? If yes, what will be changed? Can you give me some sources for info?
No, I think that person was being sarcastic (that every revision is better than the original, and they were bitter D&D was being revised). I know of no plans to revise Ultramodern Firearms.
It's possible somebody mis-remembered or poorly stated that the new d20M Ultramodern Firearms is a revised edition of a previous Ultramodern Firearms (Chameleon Eclectic's Millenium's End IIRC).
I hope you guys did not misinterpret my statement about Ultramodern Firearms "second printing" (at this time, Green Ronin is not ordering a second printing of UMF) It was just a joke which stems from an observed pattern of published products.