The upcoming Mac OS 10.7 “Lion” will not feature the Rosetta dynamic code translator. This means that PowerPC binaries will not work, period.
Nuendo 4 and 5 for Mac OS, although being themselves Universal (PowerPC and Intel) binaries, come packaged with a few PowerPC-only VST plugins. Namely, the ones outsourced to or licensed from non-Steinberg developers around 2003, 2004: DeEsser, Q, MatrixDecoder, MatrixEncoder in Nuendo 4 and Tonic, DeClicker, DeNoiser, SurroundDither in Nuendo 4 and 5.
Although I can understand their presence in Nuendo 4, released in October 2007, since it was the first Intel-ready version of Nuendo, their lingering presence in Nuendo 5, released in June 2010, is somewhat a combination of indifference and laziness.
Notwithstanding the fact that dynamic PPC code translation consumes CPU cycles that could be put to better uses, their mere presence in the Nuendo 4 and 5 packages now prevents Nuendo from starting up in Mac OS 10.7. Yesterday, I installed the 10.7 developer preview, and Nuendo 4 and 5 would not startup until I went into their packages and took out the PPC VST plug-ins listed above.
I really hope that Steinberg takes the proactive approach on this one and that the four PPC plug-ins still present in Nuendo 5 will be properly re-compiled in time for Mac OS 10.7 release.