The new batch of e-ink devices are still so new that there aren't a lot of third party accessories yet. But a new neoprene case for the Sony Reader (PRS-500) will be available in November. The case allows you to read without removing it, and offers additional protection. No indication of whether it needs to be removed to use the docking cradle or now.
From the
M-edge web site, "The Sony Reader eMotion Jacket is the ultimate for on the go eBook fanatics... [and] provide superior protection for your Sony Reader... [they] are stylish padded cases that feature a read-through design and clear vinyl screen protection so you never have to remove your Reader to use."
M-edge joined our discussions
here with some additional information in response to Stuart Young's discovery of their site.
The primary interest in third party cases for the Sony Reader will probably be due to protection concerns, because the supplied case (and Sony's optional color choices) are quite nice.
Related:
A Neoprene pouch case for the Sony Reader that seems to already be available.
An iLiad version of the M-edge case