I think a lot of people will argue that "tabular" data, or data that can best be expressed in rows and columns, should be kept in a table, but that divs were invented to replace tables as large layout elements. In my personal opinion, tables were always used as layout elements in a way that went beyond their intended purpose. That's not to say that people don't still misuse divs, for example
<div align="center">To replace a <center> tag</div>
I'd say check out A List Apart, specifically Their section on layout for tips on how to use modern compliant css-based design.
edit : My point was that this is the INCORRECT use of a div tag. In this example, you would use a style such as "text-align:center" or apply that style to the tag itself, but in this case there is no reason to wrap your text in a block-level element, because text by default is inline, so you would be better off with something more like this...
<p class="center">This is a centered paragraph</p>
and then in your stylesheet
.center { text-align:center; }
Thus, the following:
<div>Monday | Tuesday | Wednesday | Thursday | Friday</div>
<div>Work | Work | Work | Work | Play</div>
May be compliant but it looks terrible, and you'd be better off doing :
<table>
<th>
<td>Monday</td><td>Tuesday</td><td>Wednesday</td><td>Thursday</td><td>Friday</td>
</th>
<tr>
<td>Work</td><td>Work</td><td>Work</td><td>Work</td><td>Play</td>
</tr>
</table>