I used to think it would be easier to keep a clean house being home all day long than it is being gone at work all day. Silly me.
For you dads-with-stay-at-home-wives out there who sometimes come home and wonder (silently, of course): "What did she do all day?" Here's an example of what may have happened:
Mom needs to get the dishes (or laundry or something of the sort) done. But in order to do so, Baby needs to be occupied or she will be yanking on Mom's pants, begging desperately to be held or played with.
So while Mom does chore #1, Baby keeps busy by emptying the kitchen cupboard:

When Mom is done, she now has a new mess to clean up. (Lest you think I'm a terrible disciplinarian at this point, remember that this baby is not old enough to properly clean up after herself...yet). So - while cleaning up said mess, Baby happily occupies herself by emptying her diaper bag:

While Mom repacks the bag, Baby moves onto yet another cupboard in the kitchen:

Finally, Mom gives up on cleaning for a bit and does some work on the computer (posting a blog, for example). During which time, Baby does this to the office:

And after a full day of cleaning, the house is in about the same state as it was at the beginning of the day (if not slightly messier). Keep in mind that this is only a partial picture, leaving out preparation and clean up of meals, reading and playing with the baby (when she might even play with actual toys).
Still...as frustrating as some days can be, I wouldn't trade this job for any other in the world.