Using [Me] in CAML Queries
Sometimes you need to put a custom View into a List Definition. That View could be based on the current user (for example “Show all List Items assigned to me”). The problem is that the usual GUI method uses [Me] to filter the items appropriately, which breaks CAML.
The trick is twofold. First, the Value Type is “User” and second, the magic value is <UserID />. Therefore your code is.
<Query> <Where> <FieldRef="AssignedTo" /> <Value Type="User"><UserID /></Value> </Where> </Query>