Looks like the fellas over at Forge World have decided to update the old Imperial Armour books. We all just got notice that Volume One is being released in a Second Edition format that is supposedly "rewritten and expanded to be fully compatible with the 6th Edition of Warhammer 40,000."
Sounds good to me.
I haven't thumbed through my what is now "old" IA1 in a long time. Mainly because I don't do too much with Guard or the Imperial Navy aside from drool over their cool tank options.
I do think it's kinda nice to have all the new stuff collected into one book. If nothing else, it will clean up everything and you no longer need to keep up with errata sheets and updates and such. At least for the time being.
I saw the list of contents as well in the FW email, but I didn't compare it to the previous book. I think they mentioned including a couple new things, but most of it looks like it's going to be old stuff just "updated" and brought in line with 6th edition.
Maybe they'll squeeze in some new artwork too.
Make sure to check out these posts as they might help:
The Forge World Imperial Avenger Strike fighter ideas
Do you even need to buy Imperial Aeronautica?