[Voted into the WP at the March, 2011 meeting as part of paper N3270.]

Proposed resolution (November, 2010):

This issue is resolved by the resolution of issue 778.

According to 13.7.4 [temp.variadic] paragraph 4,

A pack expansion is a sequence of tokens that names one or more parameter packs, followed by an ellipsis.

This is contradicted by 7.6.2.5 [expr.sizeof] paragraph 5, which describes sizeof...(Types) as an expansion, as well as the case where the expansion appears in a declarator like the example given in 9.3.4.6 [dcl.fct] paragraph 13:

    template<typename... T> void f(T (* ...t)(int, int));

This is also described as a pack expansion, although it does not fit the syntactic summary.