Somebody out there is circulating a three-year-old tip about a close encounter between Mars and Earth. The tip is about the 2003 Mars-Earth encounter. This August, Mars will be a long, long way away, at about seven times the 2003 distance.
From SpaceWeather.com
BEWARE THE MARS HOAX: Just when you thought it was safe to read your email, a new Mars Hoax is spreading. The widely-circulated message tells us “the Red Planet is about to be spectacular. On August 27th, Mars … will look as large as the full Moon.” Not!
Fact: On August 27, 2006, Mars will be on the other side of the solar system, 385 million km from Earth and very dim. So forget about Mars. If you want to see something truly astronomical on August 27th, look east before dawn for a pretty conjunction of Venus and Saturn.
More information from NASA (from about a year ago).