Potentially cheaper to produce than regular meat (with technological advances)
Requires less food input (instead of growing a whole animal with bones & brains, you only need enough calories & nutrients to grow the muscle)
Requires less real estate (why not grow meat in skyscrapers in the city?)
Requires less water (you can use microalgae to supply nutrients to the cells instead of using water to grow corn)
Produces less waste (no solid waste and no methane gas produced from consumption of corn or grass)
Cleaner (a lab can be kept sterile; a farm cannot)
More ethical in terms of animal welfare (no suffering involved)
Healthier (scientists can have full control over fat content and nutritional content)
Prevents climate change/global warming (a recent study found that livestock accounts for 51% of man-made greenhouse gas emissions! Much of this is from animal waste and, strangely enough, methane cow burps.)
Better for public health (swine flu and avian flu originate from keeping animals as livestock; the less we do this, the fewer outbreaks we can expect. Feeding antibiotics to livestock is also feared to cause the emergence of new antibiotic-resistant strains of bacteria.)