Apparently, it's not yet commercially available.
The vest's purpose, according to the maker:
• Increases awareness of the bicyclist and bicycling as an efficient way of getting around
• Educates drivers about overtaking bicyclists safely
• Illuminates that an average person can easily bike 10-15 mph (15-25 km/h)
Looks like fun, but there will be no hiding the ugly truth on the big hills.