I just noticed today that the CAML creator application that I am using (by U2U) does not handle the today token properly (at least the version I have).
The Today token is used in views, when you want to filter on a date based on the current date. For example, if you want to set up a view that shows future events you set the filter on start date > "[Today]".
However, in CAML, you cannot use "[Today]" - the square brackets cause the query to break. Instead, you use "<Today />".
<Where><Geq><FieldRef Name='EventDate' /><Value Type='DateTime'><Today /></Value></Geq></Where>