I just happened to be outside with the dog and looked up to see the International Space Station flying over. I was quite sure that's what it was. It was extremely bright, like Venus, up around mag -3 or so I'd guess. It was in the SSE and gliding across the sky at the speed a plane would fly over but with no blinking lights at all.
It was quite beautiful since, at the same time, a high-altitude jet was passing in the other direction with a faint con trail illuminated by the already-set sun.
Data at NASA confirms the sighting for tonight at 20:49 EDT and predicts a similar flyover tomorrow evening at Mon 2011-04-18 21:14:00 -0400. (21:14 EDT). It will pass from WSE to NNE and achieve a maximum altitude (above the horizon in degrees) of 43 deg, quite high.
For more information: http://spaceflight.nasa.gov/realdata/sightings/