In fact if you go up in Venus' atmosphere to where the atmospheric pressure is equal to earth, even though CO2 is still 95%+ the temperature range is similar to earth ~32-120°F. Actually, because of this there's been talk that Venus would be the best planet to colonize 1st in floating cities. See http://www.universetoday.com/2008/07/16/colonizing-venus-with-floating-cities/
Side note: I don't have time to do the math but Mars has something like 10x the amount by mass/# of molecues of CO2 in it's atmosphere than Earth does, yet it is much colder. The reason is because the pressure is much lower
There is a simple “greenhouse” gas experiment many folks around the world who live in cold places do every day. Walk outside on a clear winter evening and you will freeze your tush off. The reason is that you are radiating infrared at a blackbody temperature of about 330 degrees Kelvin while empty space is radiating back at a temperature of 4 degrees Kelvin. Do the same on a cloudy night. Your radiative heat losses are drastically reduced because the ground is radiating to the clouds which are therefore in radiative equilibrium with the ground (because the clouds in a “grey sky” are opaque to radiation this equilibrium is quickly established). The greenhouse gas effect is why you are warm on cloudy nights and cold on clear nights.
Venus is hot because it’s basically a new planet and hasn’t cooled. Same thing explains the 90-bar CO2 atmosphere, the massive thermal imbalance, the total lack of regolith, the upwards ir flux, the random cratering, and basically every other feature of the place.