This is an unofficial snapshot of the ISO/IEC JTC1 SC22 WG21 Core Issues List revision 112e. See http://www.open-std.org/jtc1/sc22/wg21/ for the official list.
The Standard does not specify whether std::initializer_list may be an aggregate or not. Strictly speaking, the order of the bullets in 9.4.5 [dcl.init.list] paragraph 3 depends on the answer. The existence of a constructor declaration in 17.10 [support.initlist] suggests that it is not an aggregate but does not say so definitively.
Rationale (February, 2012):
The presence of the constructor declaration in 17.10 [support.initlist] is sufficient to establish that std::initializer_list is not an aggregate.