|MadSci Network: Astronomy|
Unfortunately not. Even if the largest item left behind were 5 meters across, at the moon's distance of 384,000 kilometers it would subtend only some 0.003 arc-seconds. The atmosphere of the Earth is always somewhat in motion, and it turns out this prevents seeing anything below 1 arc-second almost all the time, and only very rarely allows 0.25 arc-second of resolution. And the Hubble (not limited by atmosphere, of course) does not have a big enough mirror (it is about 2.4 meters in diameter) to resolve better than roughly 0.06 arc-seconds. But... The astronauts did leave behind some corner reflectors, and these can still be used to bounce radar/radio signals back. This has been used to measure the very slight changes in the Earth-Moon distance due to tidal interactions.
Try the links in the MadSci Library for more information on Astronomy.