Around 200 computer and video game publishers and developers are exhibiting at the 2009 Electronic Entertainment Expo, E3, in Los Angeles, displaying the latest game titles and technology.

The expo, owned by the Entertainment Software Association, was kicked off by Microsoft (MSFT) on Monday, and continued on Tuesday with keynotes from Sony (SNE) and Nintendo.  Other big exhibitors include Electronic Arts (ERTS), Sega, NVIDIA (NVDA), and Take-Two Interactive (TTWO).

Big waves were made by announcements from Microsoft on new Xbox 360 enhancements, a new PSP Go device from Sony, and several game sequels from Nintendo, as well as a number of new titles from Electronic Arts and other game developers.

Electronic Arts presented several games at the expo including NFL 10 for Xbox 360 and PlayStation 3, as well as the highly anticipated Sims 3 game for PC and Mac, which was just released Tuesday.

Also mentioned by EA were several mobile titles for iPhone and iPod including The Sims 3 as well as some that are yet-to-be-released, like Command & Conquer Red Alert, Mass Effect Galaxy, and Tiger Woods PGA TOUR.

Microsoft demoed some big enhancements to its Xbox 360 console, including Facebook access, Last.fm music streaming, instant-on 1080p HD movie and TV streaming, and a new way of controlling the console called “Project Natal.”

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This so-called “Project Natal” sensor, said Microsoft, combines a camera, depth sensor, and microphone in one device to track full-body movement and obey commands.  It can even recognize a human face and log a user into Xbox LIVE, the console’s online portion.

Among new social-networking features there’s Facebook Connect, which will let users update their status, share photos, and even post gaming updates and screenshots.  Microsoft bought a $240 million stake in Facebook in October 2007.

Xbox LIVE will also allow access to Last.fm, an online personal radio station and music social network.  Users will be able to stream millions of songs through their consoles.

Also announced is the ability to stream movies and TV instantly from Xbox LIVE in full 1080p HD.

Paul McCartney, Ringo Starr, Yoko Ono and Olivia Harrison came on the stage during Microsoft’s announcements to promote the upcoming game title “The Beatles: Rock Band,” which will be available in September.

The game will let players play songs from the band’s catalog of music.  There are also replica controllers based on the guitars the band members actually played available to use with the game.

In addition to showing several previews for upcoming PSP and PlayStation games, Sony unveiled the new PSP Go.  This new handheld gaming device is half the size and 40% lighter than the PSP-3000.  It has 16 gigabytes of internal memory.

A new service was announced called Sense Me, which will analyze the listening habits of the user and suggest music playlists (similar to Apple’s (AAPL) iTunes Genius Playlist feature).

All new game titles, said Sony, will now be released as UMD discs (for PSP models) and as digital downloads.  And the PlayStation video store will be accessible directly from the PSP Go.

The PSP Go will be available on October 1, retailing for $249.99.

Meanwhile, Nintendo unveiled a new version of its flagship Super Mario Bros for Wii.  The game, which Nintendo said will be available for the holidays, will allow up to four users to play at once.

Also announced was Super Mario Galaxy 2 as well as new games coming that will support the Wii’s MotionPlus feature that lets users control games using motion with their Wii Remote.