Image by Flickr user p0psicle As with most bugs, washing your hands with warm water and soap is a great idea.
The same bug that's plagued the Celebrity Mercury appears to being going strong in the tri-county area with more outbreaks to date this year, than in all of 2009.
I'll also recommend this piece at Wikipedia, which contains this helpful passage:
Noroviruses are transmitted directly from person to person and indirectly via contaminated water and food. They are highly contagious, with as few as ten virus particles being able to cause infection. Transmission occurs through ingesting contaminated food and water and by person-to-person spread. Transmission is predominantly fecal-oral but may be airborne due to aerosolisation of vomit. Norovirus can be aerosolized when those stricken with the illness vomit; infection can follow eating food near an episode of vomiting, even if cleaned up. The viruses continue to be shed after symptoms have subsided and shedding can still be detected many weeks after infection.
Stay healthy out there.
[Editor's note: It's worth pointing out that the cruise ship incident and the oyster incident may have come from different sources. Of course, if local oyster were contaminated that may be where the original ship outbreak came from. Food for thought, not eating.]