I have never tipped housekeeping no matter where I've stayed (except what's required on a cruise.) Is this something that a lot of people do?
It has become rather common. And there are strong opinions on all sides.
But just a point of information, housekeeping positions are paid differently that waitstaff positions.
Florida's minimum wage is $7.21 per hour. So housekeeping is being paid at least that much.
Florida's minimum wage for "tipped positions" is $4.19 per hour.
Since many states allow businesses to pay "tipped positions" a lower minimum wage like Florida does, most people know that they are expeted to tip waitstaff, etc. Otherwise, those employees won't even make minimum wage.
Since housekeeping makes at least minimum wage, some people choose not to tip them.
In our case, we tip housekeeping because they're doing rather personal things for us (handling our dirty towels, cleaning our bathroom, etc) and we figure they deserve a "thank you" for that so that I don't have to deal with those things while I'm enjoying a vacation.
Official Disclaimer: I've tried very hard to stay out of the fray surrounding whether minimum wage is an acceptable wage.