The New York Post has been giving some coverage to that angle-among others-to the story.

In fact, it even took the trouble of mentioning some of the dignataries who attended Litvinenko's funeral, one of them being Akhmed Zakayev, i.e. this guy:

One of the last Chechen rebels Russian intelligence hasn't taken Down

Some other interesting, speculative, theories:

Murder on the Polonium Express

For what it's worth, I don't think the Chechens would crap where they live.

Namely, London.

Almost all of the Chechen exiles/rebels/terrorists who are living abroad communicate via England, so I doubt that it would be in their interests to do something like this.

Al Qaeda is another story altogether.

Wow! Who knew that radiation sickness was contagious? ;)

There was a brief mention of Litvinenko converting to Islam shortly before his death this morning on, uh, Morning Edition. That doesn't exactly douse the flames.

Those crazy Ruskies!

0_o

How about the fact that Polonium of this isotope would be no good for a so-called 'dirty bomb', that the Chechens have no axe to grind with London, and that the so-called 'dirty bomb' is pretty poor as a weapon, even to a terrorist. Beyond where the conventional blast takes place, the potential for harm from the radiation diminishes quite quickly.

How about the fact that Polonium of this isotope would be no good for a so-called 'dirty bomb

Maybe, but it shows a willingness to submit to trial and error.

that the Chechens have no axe to grind with London

Can't refute that one, as I have no knowledge what the Chechens think of London.

and that the so-called 'dirty bomb' is pretty poor as a weapon, even to a terrorist. Beyond where the conventional blast takes place, the potential for harm from the radiation diminishes quite quickly.

No, but the potential for widespread panic is very much real.

I don't think the Chechens have anything against the British, but it's not inconceivable that al-Qaeda could contact this guy, play up his Chechen sympathy for their greater Islamist goals (especially if he did convert), and use his contacts in Russia to acquire materials. I read tonight that they found traces of radiation in Hamburg which can be linked to him. The plot thickens. I really hope this is just some elaborate KGB scheme.