With the new iLiad firmware 2.10.2 release, the device now supports instant dictionary look up in Mobipocket.
This is one of the important features that I have been expecting for, and I immediately downloaded a couple of demo dictionaries from the Mobipocet.com and tested it on my iLiad. It works fine, though I must have more clicks on the screen to see the defination than with my Gemstar eBook REB1200. The good thing is you can chose the dictionary you like and have more than one dictionary loaded in the device.
I purchase Concise Oxford English Dictionary today, and it works very good on the iLiad and the defination is just as good as the paper dictionary.
The dictionary instant look up is also supported in eNew in Mobipocket format by the iLiad device, though the desktop version does not.

I would like to mention as well the battery performance is also greatly improved with the 2.10.2 release, and I will have more details on this subject later on.

This was excatly the information i'm looking for since weeks.
Thanks !!!
(I don't understand why it isn't yet mentioned on the iRex Homepage or on mobipocket.com)

If only I can sync the dictionary...

I'd like more info about the iLiad: -
1. Supports mp3 files?
2. Can I listen to mp3 and read books simultaneously?
3. Zoom feature - text wraps around or horizontal scrolling? Viewing scans of books (image files) - zoom needs horizontal scroll to view left part of image
4. Dictionary - Viewing a book, can I click on a word and automatically the dictionary (separate file) opens up to that word? If so, how to get back to original book?
5. I have pdf version dictionary (editable text). Can I use this?
6. Approximate cost in USD.

Sorry for many questions - answers are appreciated.

Has anyone tried to use a larger dictionary? I am looking at the Collins English dictionary which is almost 30Mb(The concise Oxford English dictionary is 13.5Mb).

What differences am I likely to face in choosing between these two dictionaries? For example, will a dictionary lookup be slower using this over the concise dictionary?

I am using the Chambers which is around 25 megs. It seems no slower than the tiny pocket Oxford electronic one was. I think the only difference will be that you are more likely to find the word you are looking for.The Chambers is very good while the pocket Oxford often would not find a match.

The only downside will be that the bigger dictionary will take a chunk of memory but with memory prices being what they are who cares.

Thanks for the advice. I settled on the Concise Oxford English dictionary in the end, and it seems very fast.
In fact, I put a computer jargon dictionary and another couple of demo dictionaries, and it seems to be blazingly quick at searching through all of them (ie. no noticable extra lag) at the same time. I love it!