It can't find the path to the sd card so it's impossible to make backups and flash update.zips etc
The sd card however is accessible when the device is in operation as when flashing the ruu all the necessary bits and bobs are upgraded such as hboot, partitions etc.
You will notice from the thread in the dev section that the sd card doesn't work if you flash dutch dannys update.zip and i'd presume this is a result of the changes made.
Anyway if anyone wants to have a go at building cwm from the ics recovery/boot that i have and can give me a pointer on how to dump it i'd be more than happy to give it a go.
My device is s-off so testing stuff is fine too.
Worth pointing out that if i flash back to gingerbread using a stock ruu and flash cwm it still doesn't see the sd card so if you don't want to lose cwm for now don't flash the ruu.
I'll try and follow this at some point but short on free time this weekend