Blackberry has a new way for you to experience BB10 right from your mobile browser by going to blackberry.com/glimpse. They have a baked in simulator that works across a myriad of mobile web browsers (iOS, Android) and that gives you a peak inside the OS. It will not work on a desktop browser, so don't even try it (changing user agent doesn't work either :)
It's not a a full emulation, but rather just a demo of BB10′s user interactions and popular features. When you launch into it, you will get a bit of a training session on how to use BB10, what gesture controls are, etc.
Yes, it's a bit clunky because it's an emulation and it can in no way offer to you what BB10 is really going to be like, but having said that it's a nice interactive demo if you are curious about the OS and want to learn more.