Gliese 876 is a red dwarf
very much NOT Sol like. Luminosity only 1.3% of sol (according to Adam below, but that sounds in the ballpark from what I remember). Thus the 10x closer just about cancels out the 100x less luminous, and you end up with a temp in the ballpark of Mercury.
I believe I read in one of the reports that they were assuming a rather high albedo for the thing -- assuming clouds? why? -- and that might explain why 200-400C, rather than 400+ like Mercury.