A few links to the story:
The US SC Press Release Press Release Regarding Chief Justice William H. Rehnquist
CNN Article Rehnquist has thyroid cancer surgery
MSNBC Article Doctors spliton Rehnquist prognosis
CNN Analysis A Rehnquist vacancy would be huge
MSNBC Analysis Rehnquist illness sets off election alarms
It currently looks as if the Court expects Mr. Justice Rehnquist back at bench by next Monday. If he is unable to return by then, the court proceeds with the docket with 8 Justices. If he is able to be back on bench, this will have no affect on this term. If he is to be out for an extended period of time, however, this could definitely impact this term. A 4-4 vote will uphold the lower court decision.
I wish Mr. Justice Rehnquist a speedy recovery to full health.