Hello,
> Does 'openssl s_server' support this? Are there public ECC TLS
> implementations this is known to interoperate with?

You may look at Firefox source (NSS library).
In Firefox (2.0) you may view/control ssl ciphersuites entering
"about:config" url and next "ssl" as a filter word.
Next you may view/control supported ciphersuites including ECC.

Best regards,
--
Marek Marcola

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