With the long-rumored Google phone all but dead, the announcement will likely center on a new mobile operating system for phones. Google leaked that much information in the not-too-distant past. How open the operating system will be is anyone's guess, but Google will likely lean toward making it easier to develop for rather than harder.
Beyond the operating system, though, there is not much to go on. The WSJ writes that not only will the operating system be announced, but phones running the Google OS will have integrated Google applications, such as Gmail, Maps, search and YouTube. Google already makes these applications available for free on many different phones and it seems like a no-brainer that they would appear on a Google phone. If they will function better or differently on Google's OS is unknown.
Whatever Google announces in a couple of weeks will probably be exciting and might even throw the entire wireless industry for a loop, depending on how far Google takes any innovations. Until then, all we can do is twitter away the days and wait for Google to get on with it.