This is just a rumor so far but since the prices in the following table match the announced price drops by Microsoft it leads far more credibility to it. It's also expected that this will be announced at the Leipzig Games Convention.
The changes to the Core are that it will be rebranded as the Xbox 360 Arcade and include a wireless controller, 256MB memory card, HDMI, and 5 Xbox Live arcade games. It will sell at the Core's new price drop price.
source: http://kotaku.com/gaming/new-things/360-gets-european-price-cut-new-names-new-colour-291150.php