In Wills v. Foster (pdf), the Illinois Supreme Court ruled that the plaintiff should have been allowed to recover "the reasonable value of her medical expenses" without limiting this to "the amount actually paid by Medicare and Medicaid."
In so ruling, the Court reversed an appellate court decision reducing the plaintiff's award of medical expenses to what Medicare and Medicaid had actually paid. The Court also explicitly overruled Peterson v. Lou Bachrodt Chevrolet Co., 76 Ill. 2d 353 (1979), which held that the "policies underlying the collateral source rule did not apply when the plaintiff incurred no expense, obligation, or liability in receiving the services for which compensation is later sought."
The Wills case effectively does for cases involving Medicare and Medicaid what the 2005 case of Arthur v. Catour, 216 Ill. 2d 72 (2005) did for cases involving private insurance. In Arthur, the Court held that a plaintiff could submit the entire amount of medical expenses billed by health care providers without being limited by what a private health insurer had actually paid.
These details and others--such as the proper foundation for the introduction of medical bills--can be found in the full Wills opinion.