Check the news section - looks like Mointain Lion is now officially supported.
It does say that a majority of Steinberg products are supported but it doesn’t seem to say exactly which ones and if there is a dedicated Wavelab update to install that makes it work well with Mountain Lion.
On the specs & downloads page for Wavelab 7 it only mentions 10.6/10.7
I’m still not quite convinced enough to install it on my main machine. I’ll wait until I see it posted on this forum page as they did for Lion.
Actually this Steinberg article gives the all clear:
However, and perhaps PG can jump in on this… I am unable to recall my plugin presets associated with wav files I worked on under Lion 10.7.4.
Any suggestions PG?