I first heard of this in my astronomy club meeting (from someone at
Univ. of Central FL) that investigator Joseph Harrington (a UCF
astronomer) and the others indicated below had discovered day/night
differences on a close-in exoplanet. You'd think that close-in things
would be toasty warm all over, but according to the paper "Our
observed day-night flux difference..." (omitted text) "...indicates
that there is little evidence for redistribution of energy to the night
side..."

http://arxiv.org/abs/astro-ph/0610491

The phase-dependent Infrared brightness of the extrasolar planet
upsilon Andromedae b
Authors: J. Harrington, B. Hansen, S. Luszcz, S. Seager, D. Deming, K.
Menou, J. Cho, L. J. Richardson
Comments: "Director's cut" of paper to appear in Science, 27 October,
2006

Their abstract
"The star upsilon Andromeda is orbited by three known planets, the
innermost of which has an orbital period of 4.617 days and a mass at
least 0.69 that of Jupiter. This planet is close enough to its host
star that the radiation it absorbs overwhelms its internal heat losses.
Here we present the 24 micron light curve of this system, obtained with
the Spitzer Space Telescope. It shows a clear variation in phase with
the orbital motion of the innermost planet. This is the first
demonstration that such planets possess distinct hot substellar (day)
and cold antistellar (night) faces."

Is this a deal killer for tidally locked M-dwarf planets and
redistribution of heat to the 'dark side'?