VOCALOID NET - and yes, it is officially in all caps, obnoxious as that is - will be a members-only service that will turn their users into creators of Vocaloid tunes. The official press release (link text in Japanese) doesn't mention any specific voice banks by name, but if I had to guess, Miku and the Kagamine Twins will be three of the core banks available for usage at the beginning.
From the Vocaloidism link:
At launch, the platform will feature two services — VOCALODUCER, an automatic music generator service previously only available to commercial partners, and VOCALOSTORAGE, in-the-cloud storage allowing seamless transfer of song data between applications. VOCALODUCER will allow a user to create a song simply by entering lyrics and selecting a melody and singer. An advanced mode will allow selecting of musical genre, accompaniment style, and chord progressions, etc. VOCALOSTORAGE, meanwhile, will allow enabled applications to directly save and load files via the cloud.VOCALOID NET is free to join, but like many online services, paying users will get a lot more benefits, including extended online cloud storage for songs.
You can watch an official promo video for VOCALOID NET, via YouTube.