The email that many people saw describing this event was recycled from two years ago and suffered from bad spacing. It said
QUOTE
At a modest 75-power magnification
Mars will look as large as the full moon to the naked eye.
These are from the same sentence and when taken in context, would be true. If magnified by 75 times at its closest approach, Mars would appear that large. However the spacing was done badly in the email (and probably deliberately) so many people have assumed that Mars will look as big as the moon without magnification.
Mars will be close again in October this year. Not quite as close as two years ago but it won't look much different in October than it did two years ago to the naked eye. It will still be many millions of miles away and always will be.
Reference the Snopes page on this email
http://www.snopes.com/science/mars.asp