Darius Cobb, Ben McLemore's former AAU coach, told USA Today that he accepted money intended to steer Ben McLemore to agent Rodney Blackstock. Cobb says he took two payments of about $5,000 and also accepted three paid trips to Los Angeles. He also alleged that one of McLemore's cousins accompanied him to Los Angeles.
The two big questions everyone has (or should have) are "is McLemore in trouble" and "is KU in trouble?" The answers are no and maybe.
First as to McLemore, Cobb says that McLemore had no knowledge that he accepted any money from Blackstock, and even more importantly McLemore is not an NCAA athlete anymore so there's nothing the NCAA can do to him.
As for Kansas, let's take another trip into the wonderful world of the NCAA bylaws.
Rule 220.127.116.11 states (emphasis mine):
An individual shall be ineligible per Bylaw 12.3.1 if he or she (or his or her relatives or friends) accepts transportation or other benefits from:
(a) Any person who represents any individual in the marketing of his or her athletics ability. The receipt of such expenses constitutes compensation based on athletics skill and is an extra benefit not available to the student body in general
Even though McLemore had no idea Blackstock accepted money (or if his cousin did indeed go to LA, that as well) he would still be ineligible from that moment because of Bylaw 12.3.1. Further troubling is a separate allegation in the USA Today article that Blackstock paid for a birthday party for McLemore, which falls under the same umbrella of providing benefits.
What is supposed to happen in this situation is that Kansas, as soon as it finds out about the situation, is supposed to declare McLemore ineligible and then apply to have him reinstated. But with KU not knowing about it and thus unable to declare him eligible, I doubt anything happens. Bottom line is situations such as this happen with every good NBA level player every year, and it is nearly impossible to police everything. The NCAA could vacate wins if they decided there was enough evidence that McLemore and Kansas knew of the payments, but with the set of facts we have it is unlikely anything happens. Unless McLemore's former AAU coach has mountains of evidence or the agent talks to the NCAA I think KU is probably safe.
(minor edit here: John Infante makes a good point that because Blackstock was on McLemore's complimentary ticket list multiple times he probably should have known about his involvement. It could have just been a case of his mom or cousin or whomever telling him to leave tickets for a friend who happened to be Blackstock and McLemore did it no questions asked, but it could present a problem should the NCAA investigation get that far. As I say above though, I doubt it does without the agent talking or mountains of documentation emerging.)
Last note, as to why the AAU coach decided to tell about it now, reading between the lines it seems pretty obvious that the guy has fallen on hard times monetarily and probably was cut off by the McLemore camp, so he decided to go scorched earth on them, whether they are true or not. The ironic thing, of course, is that by doing this he's greatly diminishing the chances that agents will offer him things in the future.