Normally I'm an Apple enthusiast – and I really like my iPad, but I think there are some points, which make it NOT enterprise ready by now:
1) There's no remote mass setup/deployment. Every iPad has to be set up manually, manually connected to an individual iTunes account and so on. This makes it hardly possible to deploy it to a company wide audiance, like Win XP for instance.
2) There's no proper log on – the 4 digit pass might be ok, especially as you can set the ipad to erase all data after 10 false tries – but its just to easy to see if someone swipes over the the screen to make the input
3) Its not multiuser ready – you can't just buy 20 ipads and hand them out on demand for users, each one able to log on with his credentials and use it straight on.
4) Keynote, Pages and numbers may be fine for SMB use – but nearly all enterprise documents refer to a special styleguide etc. Pages and Keynote still do a bad job here. Its ok for SMB and private use though.
5) Theres no native filebrowser to access server filesystems. Of course, there's an app for that (like Filebrowser) but its not built into the system and so not useable accross apps to display, edit or modify content which resides on smb or other directory shares.
6) There are mission-critical bugs – restrictive proxy settings, which cause safari either to forget your credentials or lead to mail not able to get your saved credentials or…. simply: its a pain in the ass, and I've found several bug reports regarding this – maybe with the upcoming iOs update for the iPad these bugs have been fixed.
7) There's no access to the iPad. Yes, i know!!! This is something I don't bother, because I know which syncing app (dropbox etc.) to use. BUT: dropbox might be a restricted domain in your company network, and so people just WANT to put their USB stick into the device. Maybe this issue will be fixed, when Apple will follow the eurpoan rules regarding unified power connections with handheld devices. As far as I know MiniUSB will be a standard.
8) Presentation mode – by far the most annoying thing, and I can't get it. Why doesn't it JUST WORK. Yes: ppt/kenote presentations – but that's not the point. I want to show my iPad apps to the audience, I want them to get an impression on how apps and software will change with the ipad – but I can't show them… 🙁
I really love my iPad and won't give it out of my hands anymore. But for serious working in an enterprise environment its more or less a stylish notepad.