Steve Jobs during the iPhone OS 4.0 sneak peek event announced the release of developer preview of iPhone 4.0. Folks at Engadget have managed to install iPhone OS 4 on their iPhone 3GS and have published a hands-on video sharing their experience. Video after the jump.

Here is what they have discovered and learned about the iPhone OS 4.0 so far:

  • It’s pretty stable, especially compared to other developer editions of the iPhone OS we’ve messed around with. We haven’t had any crashes so far, and things seem mostly to be working. Find My iPhone doesn’t work, and iTunes 9.1 doesn’t know about folders and will delete any you’ve set up, but nothing major is broken, at least as far as we can tell.
  • The multitasking system works as described, but without any apps that support it it’s hard to test. Steve might say task managers are a sign of failure, but you can certainly delete icons from the switcher — just long press on them and a minus arrow pops up.
  • Bluetooth keyboards are going to be the next great iPhone accessory gold rush. Been jonesing for a million-dollar idea? Here you go: slider keyboard case with built-in extended battery. We prefer our royalties in cash, please.
  • We couldn’t get threaded messages to work in Mail, but we’re sure we’re doing something wrong — we’ve never really gotten along with iPhone Mail.
  • The zoom control on the camera is pretty slick, and there’s okayish macro. Tap-to-focus in the video mode is also a nice addition.
  • Spell check works just like the iPad, as do cut/copy/paste hardware keyboard shortcuts. Still no way to bring up the soft keyboard from the device when it’s paired, though, which is annoying if you walk away — you have to remember to turn off Bluetooth, which will undoubtedly confuse someone.
  • Faces and Events in Photos are just like the iPad — they’re just fancy folders. The actual face-detection happens on your machine, and things are just sorted on the phone.
  • Setting up a Gmail account also prompts you to sync calendars and notes — hallelujah!
  • Game Center is a barren wasteland right now, since no apps support it — we managed to log in and discover that we have no friends and no one has requested to be our friend. Suitably humbled, we logged out.
  • We didn’t have any major problems running our OS 3.0 apps, and we didn’t see any new ads or anything.

[via Engadget]