Sony finally took the wraps off the "worst-kept secret of E3": the PSP Go, the "next step in the evolution" of Sony's PlayStation portable line, complete with slide-out controls, 16GB of flash memory, no UMD drive—and a $249 price tag.

Set for release in North America and Europe on Oct. 1, the Go—announced Tuesday morning at E3 in Los Angeles—was widely expected, especially after a Sony video detailing the PSP Go leaked over the weekend.

And if you saw the leaks, you've pretty much seen the Go, which SCEA boss Jack Trenton cheerfully described as the "worst-kept secret of E3."

To recap: The new, thinner-and-lighter Go packs in a 3.8-inch display (not touch-sensitive, as had been rumored earlier), slide-out controls (with, unfortunately, just a single analog stick that's tucked to the right side of the four-key directional pad), 16GB of internal flash storage, and a Memory Stick Micro slot, and no UMD disc drive.

Sony execs took pains to emphasize that while the Go is jettisoning the UMD drive, the Go "will not replace the [existing] PSP-3000 or UMD," and that moving ahead, PSP games will be launched both as digital downloads on the PSN store and on UMD.

Unfortunately, neither the much-rumored gaming rental download service or a music store for the PSP actually materialized at E3, nor was there any word about when—or if—current UMD titles that aren't yet available for download will appear on the PlayStation online store. [Update: In a PSP Go video on the PlayStation blog, SCEA hardware marketing director John Koller says that "most" UMD games will be appearing on the PlayStation Network, although he didn't specify a timeline] Also: No discussion on whether current PSP users will be able to transfer their UMD games to the Go.

That said, Trenton announced that starting now, direct video downloads will be coming to the online PSP store (including movie rentals, I'm assuming), while 50 PSone titles will soon be available for download, including Final Fantasy VII (as of today).

Sony also announced a trio of upcoming (and mostly predicted) PSP titles: Gran Turismo (set for Oct. 1, with 800 cars, 35 tracks, four-person ad hoc multiplayer, all running at 60 frames/second), Metal Gear Solid: Peace Walker (a direct sequel to MGS3, due in 2010), and the first Resident Evil title for PSP (also in 2010).

My immediate reaction to the Go: mixed. I like the Go's new, slimmer shape, but I still haven't seen how the Go's smaller display compared to the 3000's (jaggy) screen. I'm also concerned about that single analog stick, which look awkwardly placed to the side of the directional pad. I wish we'd get an online PSP rental service, and an easy way to transfer old UMD games to the Go. Finally, the $249 price tag is pricier than I expected—I was thinking more like, oh, $199 or so.

So, what do you think? Anyone want to trade up for the PSP Go? Or will you hang onto your old PSP? Post your comments below.

Update: Here are some more detailed specs, courtesy of Sony:

• Exact dimensions for the Go: 5 by 0.65 by 2.71 inches, weighs in at 5.7 ounces (about a tenth of an inch thinner and an ounce lighter than the current PSP-3000);
• You'll be able to connect the Bluetooth-enabled Go to a Bluetooth headset or a PS3 controller; no word on cell phones, though;
• Expect an updated version of the PlayStation media manager for PC, dubbed Media Go, with an updated interface, along with SensMe, a "mood-based music recommendation system" for the PSP;
• A new "game sleep" function will let you access the Go's XrossMediaBar while a game is paused
• You'll be able to listen to tunes and watch videos (but not play games, of course) after sliding the Go shut;
• Upcoming accessories include a charging cradle and video-out cables.

[Image credits: Yahoo! News (top and bottom), and SCEA (middle)]