Measurements of rms fluctuations in interstellar dust emission at Galactic latitudes above 20° (data points with error bars) from BOOMERanG (filled circles, Masi et al. 2001, 2006) and Archeops (empty circle, Ponthieu et al. 2005). The continuous line is a thermal spectrum with T_d = 18   K and ν² emissivity. The dashed line represents rms CMB anisotropy for ΔT/T = 10^-5. The dash-dotted line represents the spectrum of the polarized signal from a dust cloud with brightness of 1 mK_RJ at 353   GHz and 10% polarization (see Benoit et al. 2004). The symbols mark the frequency bands explored by forthcoming polarization measurements from several experiments: Planck (up triangles), PILOT (squares), BLAST-Pol (stars), SPIDER (circles), EBEX (diamonds), SCUBA2 (down triangles), SOFIA (upgraded HAWC: pentagons).