The upcoming Jubeat Ripples Append is said to link with beatmania IIDX 17 somehow, and someone fishing through stuff has discovered that yes, there are hidden Jubeat songs on the Sirius hard drive that have not been unlocked yet. The person supplying this information only revealed 4 of them, but there is allegedly one more.
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We seem to have received confirmation that the extra stage system on Sirius is now becoming accessible to players, here’s what we know:
Here’s what we know:

Once you get in, you need to collect keys for each song to unlock the extra boss song on each folder (on Normal, easy clear, Hyper, AA, and on Another, [...]

You know the drill, pre-orders usually come rather early, which means that its time to start the rumor mill on what new stuff is on Empress CS. The black anothers are back in action, and two songs are confirmed to have new Another charts. Let’s go down the line here:

From Arcadia Magazine, here’s some of the goods:
Sirius AC preview:
[Hardcore] DOMINION – L.E.D.-G
New Songs:
[ELECTRO] Electrorgasm – Sota Fujimori
[DRUM'N'BASS] Troposphere – kobo
[WORLD/ELECTRONICA] Tori-no-kimochi – 猫叉Master+
[乙女ハウス] Sunshine Hero – kors k feat.Mari*
[DRUM'N'BASS] FLAG OF PEACE – GUHROOVY fw. NO+CHIN
[BOSSA ELECTRO] Gymnopedie 009 – Studio Bongo Mango feat. Junko Wada (BE THE VOICE)
[HAPPY HARDCORE] RIZING YOU UP – [...]

Sources seem to suggest that the next beatmania IIDX game will be released on October 21, 2009.
Of course, you will know everything and everything on release day here for both Sirius AC and Empress CS, so stay tuned.

A Purotota user has unearthed the full boxart for Empress CS, which proclaims among other things:
Archives Mode: 500 pieces of artwork from past games.
Oh boy.