BG Render is great, but it doesn't do all that Nucleo Pro does/did.
One feature that After Effects CS6 has built in that is similar to a feature in Nucleo Pro is Cache Work Area In Background.
There are some resources about that feature and some related features
here.
Also, you can now render After Effects compositions in the background with Adobe Media Encoder... which most people seem to miss.
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Todd Kopriva, Adobe Systems Incorporated
product manager, professional video software
After Effects team blog
Premiere Pro team blog
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