Here is a quote from Nik’s FAQ on their support site.

We are continuing to evaluate support for Aperture 3. Initial tests have uncovered some issues that we are currently working with Apple to resolve.

The following products are currently not fully compatible with Aperture 3:
Color Efex Pro 3.0
Viveza 2
Silver Efex Pro
Sharpener Pro 3.0

Dfine 2.0 appears to be working in Aperture 3 running in 32-bit mode without issue, however we are working with Apple to perform additional compatibility tests.

We will provide updates to all registered customers as soon as additional information is possible.”

So.. it looks like they are working on it but there is no time line right now.