Yep you read that right, they added an R to the title. And as the video on the main website shows, they're adding a lot of new moves to existing characters. No word on if this is a complete rebalance or something like BlazBlue's overpowered-for-the-jokes Unlimited characters.
Edit: this appears to be an actual rebalance.

They've also added some UI changes like Eddie's shadow gauge being by the tension meter, invalid combos showing you which hit is invalid, and the stagger icon has a meter showing how much hitstun remains.

They also mention a Location Test on June 2nd in a few locations in Japan. See the official site for details.

http://www.guiltygearx.com/

we've been compiling the changes listed on the site as well as those observed in the video here:
http://www.dustloop.com/forums/showt...39#post1333839

Team 2A was present at last weekend's Winter Brawl and recorded match vids of Blazblue and Guilty Gear! Come see the tournament debut of quite a few up and coming east coast talent in BB and some great GG matches to help you get hype for the re-release!

Playlists:

BB: http://www.youtube.com/playlist?list...9&feature=plcp

GG: http://www.youtube.com/playlist?list...6&feature=plcp

Seriously, how do Steve H. and Marlin Pie have better matches every major?

The long wait is finally coming to an end, as ASW has announced that their arcade port of Guilty Gear Accent Core Plus will see a release on XBL and PSN in the future with netplay enabled! Stay tuned for more info!

Source: http://www.arcsystemworks.jp/index.cgi?eid=556