One of the many reasons that we at ONE/Northwest like to do web development using Plone is because there are serious companies investing serious money in it.
A great example of this is the Goldegg initiative, which is being organized by Cignex, a leading Plone/Zope development shop and funded by one of their large public-sector clients. They’ve even just put out a press release.
Goldegg is going to do a bunch of “plumbing” work on the Plone/CMF/Zope stack, the end result of which will be a “future-proof” Plone that is suitable for serious enterprise content management projects.
What I love about this is that it lets smallfries like us leverage much larger investments by big customers. And unlike corporate investments in PHP or MySQL, which are also good, these investments are much, much closer to the website end-user.