Michael,
Do you mean the value that the property returns, or if the property
exists? If it is the former, then you can just check the value, and compare
against null. However, if the return type is a value type (as others have
mentioned), then this is impossible, because value types can not be null.
However, if you want to see if an object implements a property, then you
can use the GetProperty method on the Type representing the type of the
object, checking the return value against null. If it is null, then the
property does not exist.
Hope this helps.