I've spent the last month putting together a rtw trip via the trans-mongolian railway. I was focussed on train reservations, and thought two months ahead was good for Naadam accommodation, but I was obviously wrong. I will be there from 5th - 12th July. At this stage are there any options? Is it still worth emailing hostels etc? I am not sure what to do here - never come across this sort of advance booking before. I'm not comlaining, big trip and I just missed this part of the preparation -- just looking for help.

Consider going to a Naadam outside of UB. In the US, the most authentic County Fairs are in the less populated counties. Day one of Naadam last year I was in a town with zero tourists. Day 2, in a town with about 8. The real deal.
Just be aware that Naadam dates can vary by a few days in different locations.
Will
Hi Hoolie
I agree with Will, you may want to consider Naadam in the countryside.
The tourist information at the central post office will suggest options with locations and dates.
Countryside Naadam in some cases is before or after the official dates of July 11-12.
(because countryside officials and popular countryside competitors are busy in UB during the official dates).
It may seem that Ulaanbaatar hotels are booked in advance for July, (which is true) but -
1. they are over booked by tour operators that want to ensure space for their customers.
2. You have a better chance with the budget hostels - so keep emailing them, and try again just before you leave.
3. Once in UB, check around, as travelers don't show up or change plans.
4. A recent unofficial phone survey I made on hotel capacity in May 2009 indicate a slowdown in tourism to Mongolia.
Links
List of accommodation options in Ulaanbaatar
Naadam is the most colorful time in Mongolia
Dan

I don't agree with Dan and Will.
If you know what to do during Naadam in Ulanbator, it is far more better than Naadam festivals in countryside.
It is more comercial but it is more professional in UB. Yes, there are less tourists in countryside Naadam but often there is no archery, or wrestling competition is just among the boys and even sometimes they wear american basketball shoes.
In UB, every event timing is acurate, and more interesting.

Hi Hoodi,
I know how you feel; I went through this a few weeks ago and I was very surprised by this. One of the guesthouses which was full suggested I contact LG Guesthouse, I did and I was impressed how quickly they got back to me, furthermore they promised me a ticket for the festival as well. this is their email address:
lg@mbox.mn.
hope this helps ;
Julie

Thank you to all of you. I am sure somewhere will come up - just emailed LG. Ideally I'd try to get out into the countryside the week before, then spend the 11th watching the opening day in UB. I'll be travelling alone, so hope to see some of you there. Thanks!

The tour company Gobitours now have a guesthouse right in the centre of UB. It's not listed
on many sites yet so not many people know about it. They might have space then.
Try e-mailing Enkhtuya at gobitour@yahoo.com