Penryn supports only SSE 4.1 so the answer is no — it is not supported.
Yes, I understand the Penryn emulator doesn't support SSE 4.2. However, the purpose of that emulator was to allow software developers tostart writingcode before Penryn was released.
You may have noticed Intel intends to support an AVX emulator in Q1 of next year. Nehalem should be released before the end of this year with SSE 4.2 opcodes. So does Intel intend to supply an emulator to support the new SSE 4.2 opcodes in Nehalem prior to its release or are those opcodes so specialized that Intel doesn't expect average software developers to implement them?
I understand. Unfortunately, you will have to wait for someone from Intel to answer that.
On a side note, if you simply asked "Are there any plans for releasing an SSE 4.2 emulator and if so when?" you would have gotten the answer much sooner.