This is an announcement for the paper "A noncommutative version of the John-Nirenberg theorem" by Marius Junge and Magdalena Musat. Abstract: We prove a noncommutative version of the John-Nirenberg theorem for nontracial filtrations of von Neumann algebras. As an application, we obtain an analogue of the classical large deviation inequality for elements of the associated $BMO$ space. Archive classification: Functional Analysis; Operator Algebras Remarks: 35 pages The source file(s), jnir3.tex: 96625 bytes, is(are) stored in gzipped form as 0410121.gz with size 29kb. The corresponding postcript file has gzipped size 134kb. Submitted from: mmusat@math.ucsd.edu The paper may be downloaded from the archive by web browser from URL http://front.math.ucdavis.edu/math.FA/0410121 or http://arXiv.org/abs/math.FA/0410121 or by email in unzipped form by transmitting an empty message with subject line uget 0410121 or in gzipped form by using subject line get 0410121 to: math@arXiv.org.