Updated 3:04 p.m.
In a turn from what Mark Emmert originally said about the Jerry Sandusky/Penn State scandal, it was revealed a few moments ago a statement that the NCAA will in fact be launching an investigation into the Penn State athletics program.
The letter, as received by Penn State today:
"I am writing to notify you that the NCAA will examine Penn State's exercise of institutional control over its intercollegiate athletics programs, as well as the actions, and inactions, of relevant responsible personnel," Emmert wrote. "We recognize that there are ongoing federal and state investigations and the NCAA does not intend to interfere with those probes."
Update 1 (2:57 p.m.): Here is the full letter (click to download).
Update 2 (3:00 p.m.): This looks to be the first time ever that Penn State will be investigated by the NCAA for such serious violations. Ben pointed out on Twitter (saving me time, thanks, Ben!) that "Bylaws in question include: 19.01.2, 10.1, and Institutional control which is found in (2.1, 6.01.1 and 6.4)."
Update 3 (3:02 p.m.): It's also good to remember in this case, that an "investigation" isn't the same as a "notice of allegations." The former is simply a preliminary step by the NCAA to find out if Penn State even possibly did anything wrong, like building a case before pressing charges; the latter is like pressing charges.
Update 4: (3:04 p.m.): Chris hits the nail on the head with this: "NCAA is more interested in looking like they care instead of caring. That's their thing: concern trolling." Uh, yup.