This is an announcement for the paper "A sharp equivalence between $H^\infty$ functional calculus and square function estimates" by Christian Le Merdy. Abstract: Let T_t = e^{-tA} be a bounded analytic semigroup on Lp, with 1<p<\infty. It is known that if A and its adjoint A^* both satisfy square function estimates \bignorm{\bigl(\int_{0}^{\infty}\vert A^{1/2} T_t(x)\vert^2\, dt\,\bigr)^{1/2}_{Lp} \lesssim \norm{x} and \bignorm{\bigl(\int_{0}^{\infty}\vert A^{*}^{1/2} T_t^*(y)\vert^2\, dt\,\bigr)^{1/2}_{Lp'} \lesssim \norm{y} for x in Lp and y in Lp', then A admits a bounded H^{\infty}(\Sigma_\theta) functional calculus for any \theta>\frac{\pi}{2}. We show that this actually holds true for some \theta<\frac{\pi}{2}. Archive classification: math.FA Mathematics Subject Classification: 47A60, 47D06 Submitted from: clemerdy@univ-fcomte.fr The paper may be downloaded from the archive by web browser from URL http://front.math.ucdavis.edu/1111.3719 or http://arXiv.org/abs/1111.3719