Figure 1 from "The M-sigma and M-L Relations in Galactic Bulges and Determinations of their Intrinsic Scatter" by Gueltekin et al. (http://arxiv.org/abs/0903.4897v1):
Caption (Abridged): "The M–sigma relation for galaxies with dynamical measurements. The symbol indicates the method of BH mass measurement: stellar dynamical (pentagrams), gas dynamical (circles), masers (asterisks). Arrows indicate 3sigma_68 upper limits to BH mass. The color of the error ellipse indicates the Hubble type of the host galaxy: elliptical (red), S0 (green), and spiral (blue). The saturation of the colors in the error ellipses or boxes is inversely proportional to the area of the ellipse or box. Squares are galaxies that we do not include in our ﬁt. The line is the best ﬁt relation to the full sample: MBH = 108.12 Msun (sigma/200 km s−1 )4.24. The mass uncertainty for NGC 4258 has been plotted much larger than its actual value so that it will show on this plot."
Interesting Plot showing the latest and most reasonable collection of galaxies with dynamical BH mass estimates, along with a statistically sound investigation of the Msigma relation and its intrinsic scatter. They find a scatter of (log-normal) e_0=0.44±0.06 (0.31±0.06 for ellipticals only), which could be physical or systematic uncertainties in the observations.