I think this highlights part of the problem...
I've mentioned the transition and convergence... and part of that is the architecture support to enable these to happen. All of the technologies needed to fully realize the promise of tablet computing for enterprise use aren't in place yet. That is delaying transition. I really dig the Nexus 7 - but the Samsung Galaxy Tab 7.7 had one serious advantage - 4G connectivity. The problem is that it needs to be as inexpensive, unlimited and ubiquitous as traditional connectivity in order to become meaningful. The Nexus 7 is designed to *encourage* leveraging cloud technologies - but what good is a mobile device that requires the cloud when you don't have connectivity *to* that cloud? So Google has addressed this with clumsy work-arounds like offline cloud-apps and limited sync of last documents that were accessed, allowing users to manually pre-cache data (offline maps, "pinned" music and movies). These are inevitably unsatisfying and limited solutions. They offset the convenience by making the end user carefully consider and plan what they're going to need and when and where they're going to be "off-the-grid".
In the meantime, even 3G or 4G connectivity is not dependable enough, is too expensive, and must be carefully managed for bandwidth consumption compared to traditional connectivity methods. So the Wireless Telcos are a big obstacle holding back the rampant adoption of tablets in the enterprise, right now. Effectively, tablet technology *connectivity* is at about the place where the internet was when dial-up modems were 33.6k... maybe not even quite there. The pipe, the availability of that pipe, is what limits the practical application of the device. It is one of the big bottlenecks slowing down adoption.