Querying in CAML Relative to Today's Date

Found little information when searching for ways to perform date queries using CAML relative to today's date - only one reference to the use of OffsetDays from the article Customise the Content Query Web Part . Surprising the lack of information on this technique.

Here's the example from that article:

<Where>
  <Gt>
      <FieldRef Name="Created" Nullable="True" Type="DateTime"/>
      <Value Type="DateTime"><Today OffsetDays="-7"/></Value>
  </Gt>
</Where>