Cleaning....is it really considered cardio?

Cleaning/heavy vigorously. Its listed on the exercise side of this site. :-)

Yes, absolutely. Think about it. It is an aerobic activity. You are in a near constant state of motion, especially when doing it as a job. For logging, there are two options, "light moderate" and "heavy vigorous". Since I am a professional house cleaner, I absolutely log my time as exercise. I go up an down staircases, lugging heavy vacuums, cleaning supplies, and other equipment. I am reaching high, bending/squatting low, pushing, pulling, lifting, walking around the house/building, going to and from car, and using various leg and arm motions to get the job done within a specific amount of time. Not to mention balance, and strength. I bet this sounds a lot like what you do. Again, think about the motions, and how long and intensely you are doing it. I like to estimate low, so I typically use the "light/moderate" estimate for cleaning, but heavy/vigorous is no stretch. Both are a modest burn, especially when cleaning for 4, 5 hours (and more!) straight. If you were cleaning at home, and taking lots of mini-breaks (and/or getting side tracked with slower moving/not moving tasks) then I would underestimate even further.
For reference: Plus, the more you weigh, the more you will burn. Burning calories at 250 per hour of activity is not high, but it sure adds up, and utilizes various body parts. As opposed to using the elliptical for an hour, or going snow shoeing which could easily burn 600-1500 an hour.
Make sense?