According to Ulf Möller there will be a patch made before the next release to isolate the ECC code in case of patent concerns. The ECC code can be included or excluded based on a configure flag like the present RC5 and IDEA algorithms which are still patented in various parts of the world.
Compile-time flags already exist to turn on and off ECC code in OpenSSL - they are OPENSSL_NO_EC, OPENSSL_NO_ECDH, and OPENSSL_NO_ECDSA. Additionally, there's a compile-time flag to turn on or off the code that is allegedly encumbered by Sun patents and a compile-time flag to turn off code that might be encumbered by another company's patents.
Furthermore, this is not new to OpenSSL nor to the crypto world in general. Lots of algorithms included in OpenSSL are covered by patents, RC5 and IDEA being prime examples. The OpenSSL license and most other open-source licenses only give you rights to copy and distribute the code, not necessarily to use it. Just as it was illegal to use RSA cryptography in the United States before Sept. 2000 without licensing it from RSA Security, so too is it illegal to use RC5 without licensing it. The OpenSSL license does not and cannot grant you those rights.
The Sun provision is there to grant users additional rights. As the previous poster indicates, it allows you to use any algorithm that Sun has a patent on in the context of OpenSSL and be free from threat of patent infringement lawsuit provided you don't sue Sun over a related issue.
Is it reasonable for Sun to ask you to not to sue them for code they gave away for free in return for not suing you? That's a business decision you make when you decide to use OpenSSL code.
Is it reasonable for Sun to say you can use the encumbered code in the context of OpenSSL but not in other contexts (like a hardware accelerator)? Under US law, they've got the right to do that. Whether you agree with patents or not is a different argument.