Namco Museum DS is a traditional collection of a handful of Namco's 1980s arcade catalog. The company has had tons of great hits over the years, and on the DS, the emulation seems pretty good so far.
The version being shown at E3 contained Galaxian, Pac-Man, Galaga, Xevious, Mappy, Tower of Druaga, and Dig Dug II on the classics side. A version of the four-player Pac-Man Vs. is also available, and can be played using one copy of the cart. Demo versions of the classic arcade games can be sent wirelessly, as well.
We quickly moved through the available games, and the emulation felt pretty accurate. The games all run on the top screen, and there are plenty of screen-stretching and screen-rotating options. You can also adjust the games' difficulty and other interesting options, such as choosing between the original version of Galaga and the bug-fixed version, which removed the problem where you could trick the enemies into not firing at you.
All in all, this looks like it could shape up to be a decent portable collection of some of Namco's arcade greats. Namco Museum DS is currently scheduled to hit shelves in September.