I'm not familiar with the total history of how Big Corporate Tech Entities deal with their acquisitions, but here is a data point:
Yahoo selling Kelkoo (or divesting as they call it) » Crowdstorm (the blog)
The Yahoo/Kelko deal with about 3.5 years ago, enough time for -
* the founders to leave
* original crew to breakup
* a stronger focus on the bottom line, quarterly numbers and all that good stuff
Those 3 things seem to be a common (inevitable?) occurrence for these situations. Then again, Zimbra is not Kelko, it's:
* in a different time period and investment atmosphere
* a different product
* in the Bay Area
* possibly a better fit in the grand scheme of things according to the of the Yahoo Corporate Strategy wizards who are thinking 6 steps ahead of everyone else
So maybe I should have no reason to confidently say "give it 3 years for Big Corporate Parent to erode away The Acquisition's innovation and culture" - but give it 3 years to enhance innovation and culture.
Bah - who says in 3 years I'll be working at a place that wants me to admin Zimbra, but it's always fun to try to predict.