The new "Daily Plan" is available to use on all of Verizon's connected devices including tablets and the Samsung Galaxy Camera. You can use the plan for as many days in a row as you want, but at some point you might as well pay $10 to add the tablet to a Share Everything plan, or just sign up for a monthly plan for the slate. And it isn't nearly as good as the free 200MB a month that T-Mobile is giving tablet users who are T-Mobile customers. Heck, the tablets don't even have to have been purchased from T-Mobile.
If you're a Verizon customer, this is a way to hook up a tablet that you normally use with a Wi-Fi network. Perhaps you're visiting your in-laws for the day and they don't have Wi-Fi. Instead if leaving your tablet at home, you could buy the 300MB of data from Big Red to tide you over until you return home later that evening.
source: Verizon via AndroidCentral