Somebody know more about that matter?
On the Chinese news it looks like the entrance to Tibet is only forbidden for backpackers but it's allowed for tour groups.

It doesn't look very clear to me.

ABC news article:
abcnews.go.com/[...]

I read another article which I can't find the link to anymore, that the Chinese are not issuing any more permits to enter Tibet, period. The policy has always been you need to have a permit to enter Tibet and such permit is only issued to certain travel agencies and tour guides. These agencies are given a list of rules to follow and it includes controlling the tourists and make sure they follow the rule as well or they risk being black listed.

Any foreigners caught in Tibet without said permit are usually immediately expelled and blacklisted from ever entering China again. If there are extenuating circumstances (usually none) then they might take it easy on you and levy a heavy fine. If they suspect you of spying or causing trouble or for some reason is just pissed at you, then you'll disappear from the face of the earth never heard from again.

The Chinese government do not kid around when it comes to Tibet. Living in Beijing and Shanghai, and even Kunming, we sometimes forget that China is an autocratic state with their somewhat laid back attitude towards foreigners. However, don't test their patience with Tibet.

Cheers~

Oh geez, here we go again. Tibet is such a beautiful region and they're preventing foreigners, who most likely recognize that Tibet is a legitimate part of China from going there? Why?

Reading a number of articles over the last few weeks.
This is a sensitive period. There is a big Buddhist festival, lasting one month, that usually attracts protesters. There has just been an anniversary of a big event in Chinese recent history. There has been an 'inflammatory incidents' in the region in the last week or so.
Add to this there is a big changeover of leadership coming up in Beijing.

This closing of access has happened before at sensitive times, and has always only been a temporary measure. I am sure the tour groups will be allowed back in after a period of time.

Perhaps Tibet is closed to protect the safety of foreigners from rioting, rampaging separatist terrorists?

Normally Buddhist festivals attract tourists including international visitors that could bring in lots of needed revenue especially to a poor region like Tibet. But well, I guess that's just wishful thinking on my part - if Tibet were in Thailand or Laos there'd be half a million foreign tourists visiting that festival, but well, I digress.

@laotou, that is probably the reason, but for some reason I can't wrap my head around that possibility since for me Tibet is Buddhist and Buddhists can't possibly be violent. At least that's the image I have in my mind. So that makes my first "question" quite a obviously a rhetorical one.

It's going to be a big impact for their tourism income... and who knows how long this ban is going to last.

oh, buddhists can be just as violent as other religios groups, just take a look at Sri Lanka.

Anyhow, back on track; do you guys think this will affect our (i.e, foreigners) ability to travel to Qinghai and other culturally tibetan areas outside the TAR?

no forbiden for foreingers to travel to other cultrually tibetan areas out the TAR. I went there with my Italian passengers last year. and foreingers can go to tibet if accompanied with a certified guide and allow to travel on designated route (thats the concept of tour group).