Update, 23rd of June: According to some sources, the patch will be available on Friday.
In a forum post on the official forum, Cyanide has revealed a few minor details of the upcoming patch for PCM10. In fact, the post is primarily meant to answer some of the critism that have been directed at Cyanide for not including enough stages with the game.
In response to this, they say that they have been asked to make the patch as small as possible, making it impossible for them to include more stages with the 1st patch. Instead, you will have to wait for the 2nd patch for more stages. The 1st patch is primarely aimed at bug fixes, and according to Cyanide, it has already been sent to 'validation' - meaning that it shouldn't be long before it's released.
For those who have already started a career, it's been mentioned that a tool that can synchronize the DB-differences between the patch's DB and your save games may be provided.