The story...

An Israeli company called Odigo received advanced warning of the attacks. Here’s Alex Jones take on the story:

Odigo admitted publicly... that yes, they got a warning, an Instant Message, hundreds of their employees, in the Towers, and told them, to leave the building, 4 hours before the planes slammed into it. This is on the record and cannot be ignored.
Alex Jones
Martial Law 911

And repeated in one of his radio interviews...

Odigo admits that they instant messaged their people to get out of the building.
http://www.prisonplanet.com/articles/march2005/300305newrevelations.htm

Our take...

Jones makes a dramatic story, and from this account you’d think the case was proven. After all, a warning that saved hundreds of lives cannot be ignored, right? Trouble is, what he’s saying isn’t exactly accurate. Let’s look at the original report.

Odigo, the instant messaging service, says that two of its workers received messages two hours before the Twin Towers attack on September 11 predicting the attack would happen, and the company has been cooperating with Israeli and American law enforcement, including the FBI, in trying to find the original sender of the message predicting the attack.

Micha Macover, CEO of the company, said the two workers received the messages and immediately after the terror attack informed the company's management, which immediately contacted the Israeli security services, which brought in the FBI.

"I have no idea why the message was sent to these two workers, who don't know the sender. It may just have been someone who was joking and turned out they accidentally got it right. And I don't know if our information was useful in any of the arrests the FBI has made," said Macover. Odigo is a U.S.-based company whose headquarters are in New York, with offices in Herzliya.
http://www.haaretz.com/hasen/pages/ShArt.jhtml?itemNo=77744&contrassID=/has%5C

So, problem #1 with Jones account: the company say nothing about telling their employees to “leave the building”. They told no-one about the message until after the attacks. But didn’t they feel under threat? No, these employees were in Israel, not America.

Alex Diamandis, vice president of sales and marketing, confirmed
that workers in Odigo's research and development and international
sales office in Israel received a warning from another Odigo user
approximately two hours prior to the first attack.
http://amenusa.org/prior.htm

Still, the message did predict the attack, right? Maybe not.

Odigo Vice President of Sales and Marketing... Alex Diamandis today in a telephone interview also said the warning message did not identify the World Trade Center as the attack target.
http://amenusa.org/prior.htm

That explains why they didn’t notify their employees in the towers, then -- they didn’t know the attack was coming after all. In fact for all we know, the message could have been something very vague that only seemed meaningful later: “America will pay for its crimes, and sooner than anyone believes”. That seems plausible from the comment Alex Diamandis made in another article.

"Without going into details, the message was most noteworthy due to the timing, not due to the substance of the 'warning.' It could easily be coincidence," Diamandis said.
http://www.atnewyork.com/news/article.php/8471_893851

There is another reason why Odigo didn’t alert their WTC employees, of course. They didn’t have any offices there.

Odigo's New York office is located four blocks from the site of the World Trade Center, in an area that was blocked off for a short time following the attacks.
http://www.fpp.co.uk/online/01/09/WTC_Odigo2.html

And just by way of completeness, it doesn’t even seem Odigo had “hundreds” of employees to flee the WTC office that, uh, they didn’t have.

[June 13th 2001]
The Odigo team consists of 80 employees.
http://www.ruksun.com/html/news/odigo.html

And also, once you know the full story, another question comes to mind. If this is supposed to be a "warning", why send it to people in Israel who would be unaffected by the event? And not give them enough information to warn colleagues closer to the attacks, in New York? It doesn't make sense, and without knowing the message text, it certainly doesn't prove foreknowledge.