Western Digital recently (a week ago) presented two new NAS drives from their World Edition series.
There are two (but it seems that actually, 3) models in the range:
My Book World Edition (single drive 500GB, Ethernet, 1xUSB) and
My Book World Edition II (dual drive 1.0TB, Ethernet, 1xUSB).
I also saw some 320GB models but not quite sure where these came from.
RRP is quite surprising for 500GB model - 159 quid. Which means we should expect price to be around 130 quid soon. It seems to be that this is the cheapest 500GB NAS avaible. The 1TB price is quite steep - 299, which puts it in direct competition with Buffalo Linkstation, HP MV2010/MV2020, Thecus and such.
Amazon is offering it for http://www.amazon.co.uk/exec/obidos/ASIN/B000MSVNM4/pricerunner-21/ref=nosim
£136.72 but with 4 weeks delivery.
So, if someone (like me) is looking for cheap NAS then this might be a good option :)