T-Mobile's teaser page promises that "Later this year, the first HSPA+ smartphone from T-Mobile will shape the next generation. Yours" and offers a sign-up page for receiving information on the launch. If you head over to the teaser page right now and view the source code, you can see the reference to the "Vanguard" yourself - as well as the "Sidekick", which was thought to be the phone's T-Mobile branding.
It's all getting a little complicated, with too many rumoured names muddying the waters. T-Mobile's G1 successor was thought to be part of their so-called "Project Emerald" and will prove the return of the first ever carrier to support Android. It's been a long time coming for those of us who bought the G1 and haven't been offered a worthy phone to upgrade to.
As per usual, specs are flying about the place, but what we've heard about the Vision/Vanguard/G1 Blaze is that it'll have a 3.7-inch display, 1GHz processor and will contain a slide-out QWERTY keypad. Not to mention that HSPA+ T-Mobile's product page is touting. [T-Mobile via PhoneScoop via TMO News via BGR]