This is an announcement for the paper "Metric spaces with linear extensions preserving Lipschitz condition" by A. Brudnyi and Yu. Brudnyi. Abstract: We study a new bi-Lipschitz invariant \lambda(M) of a metric space M; its finiteness means that Lipschitz functions on an arbitrary subset of M can be linearly extended to functions on M whose Lipschitz constants are enlarged by a factor controlled by \lambda(M). We prove that \lambda(M) is finite for several important classes of metric spaces. These include metric trees of arbitrary cardinality, groups of polynomial growth, some groups of exponential growth and certain classes of Riemannian manifolds of bounded geometry. On the other hand we construct an example of a Riemann surface M of bounded geometry for which \lambda(M)=\infty. Archive classification: Metric Geometry; Functional Analysis Mathematics Subject Classification: 26B35; 54E35; 46B15 Remarks: 71 pages The source file(s), lip.tex: 181271 bytes, is(are) stored in gzipped form as 0404304.gz with size 53kb. The corresponding postcript file has gzipped size 191kb. Submitted from: albru@math.ucalgary.ca The paper may be downloaded from the archive by web browser from URL http://front.math.ucdavis.edu/math.MG/0404304 or http://arXiv.org/abs/math.MG/0404304 or by email in unzipped form by transmitting an empty message with subject line uget 0404304 or in gzipped form by using subject line get 0404304 to: math@arXiv.org.