The Wall Street Journal, not exactly a liberal newspaper reports:
The plan would essentially end Medicare, which now pays most of the health-care bills for 48 million elderly and disabled Americans, as a program that directly pays those bills. Mr. Ryan and other conservatives say this is necessary because of the program’s soaring costs [….]
Mr. Ryan’s proposal would apply to those currently under the age of 55, and for those Americans would convert Medicare into a “premium support” system. Participants from that group would choose from an array of private insurance plans when they reach 65 and become eligible, and the government would pay about the first $15,000 in premiums.
Talking Points Memo has a lot more details.