They are currently working on the "Blue Line".
Substitute service between O’Hare and Rosemont
3 a.m., Tue., July 8 to 3 a.m., Mon., July 28, 2008
Bus shuttle service will replace rail service between the O’Hare Bus/Shuttle Center (located directly above the O’Hare CTA station) and Rosemont station from July 8 to July 28.
At O’Hare customers will board and alight buses at the O’Hare Bus Shuttle Center located in the airport’s lower level near the flight Arrivals area (O’Hare terminals 1, 2 and 3). The bus shuttle trip between Rosemont station and O’Hare takes approximately <NOBR>10 minutes.</NOBR> CTA personnel will be available at both locations to direct customers to awaiting buses.
At Rosemont, you can board the Blue Line, and continue your ride in to the City.
http://www.yourcta.com/
HTH -
Darcy