One of these batteries will soon be available in the U.S. market - the other is about to be released in Germany.

Milwaukee just announced several upgraded batteries designed to work with existing M12 and M18 tools. There will be 2.0 Ah compact models and 4.0 Ah high capacity models in both voltages (see photo below). A number of companies already make 4.0 Ah packs for 18-volt tools but Milwaukee is the first to announce compact 18-volt packs rated higher than 1.5 or 1.6 Ah. Their 2.0 and 4.0 Ah M12 packs will be the first of that capacity for subcompact (12 volt max) tools. These upgraded batteries are scheduled for release in January 2013 and will be available separately and in select tool kits.

Chris over at Tool-Rank was poking around on Bosch's German website and found a cordless rotary hammer with a 4.0 Ah battery. Here's a photo and a press release from that website (if you look closely you can see 4.0 printed on the pack). This battery does not appear to be available outside of Germany and cannot be found on the company's French and U.K. websites.