Radioactivity is nasty stuff, and when you've got radioactive surfaces all over the place, trying to clean them up often just results in your cleaning supplies becoming radioactive as well. This blue goo neatly takes care of the whole problem, capturing radioactive particles and storing them while simultaneously cleaning better than a scrub brush.
The blue gooey stuff is called DeconGel, and its properties were discovered entirely by accident back in 2006 when researchers running an experiment slopped some of the blue gel they were working with onto the floor without noticing. When they saw the mess the next day and peeled up the now-hardened polymer, the floor underneath was spotless, and they couldn't replicate that level of cleanliness on nearby parts of the same floor, even with cleaning solution and scrub brushes.
Essentially, the gel is able to completely encapsulate anything that's not nailed down (on the microscopic level) to any surface that it's applied to. This includes dirt of course, but also microscopic radioactive particles and other contaminants and pollutants. You spray or paint the liquidy gel onto a surface, where it solidifies into a polymer, and then you simply peel it off, roll it up, and dispose of it, keeping everything it's glommed onto safely contained.
DeconGel is currently being used in the hundreds of gallons to help decontaminate surfaces in Japan, but it's already commercially available here for about $160 per gallon, which is enough to cover up to 100 square feet. That may just be enough to decontaminate your bathroom, but you might want to give it a couple coats just to be sure.