It's finally officially here! I just started can't wai!
I can confirm that it isn't out on the old website which I still have - I started it on the iOS app and it let me move onto a computer after having started the course on my iPod. I do hope that it appears soon, though, as whenever I start a new tab of Duolingo it redirects me to a new users' page which can be very annoying...
If it's not integrated (I wouldn't know, I don't have access to it yet) you can install a Japanese keyboard in your PC's keyboard options. If you're on windows, you should then just have to switch to it using the control panel in the bottom right (I'm not sure about other platforms) and then you just type in romaji and it should convert it to hiragana as you type.