For business use the iPad can replace a laptop, however before embarking on this path I always inform clients that they need to do research on their daily software usage and workflow, taking that into consideration 90% of users feel they can then replace their trusty laptop but often fall short in the workflow due to the closed system of iPad OS.
This is remedied by workflow training that I then provide with correct iPad software replacement.
Some points that crop up often:
As a mobile device for viewing data with minimal editing it works well.
Note taking in meetings : excellent
Replacing complex spreadsheets : not bad but has limits
Advanced email: not bad but with limits
In my case it replaced my Netbook which had a 7 hour battery life and a 3G dongle, it still took me 6 months of research before hand to buy the iPad1 , as the price was similar to a laptop in my country, I had to justify the cost.
A year later I'm on my 2nd iPad the new iPad 3 and I have converted my total daily business usage to 95% on iPad and only do advanced accounting and spreadsheets on the PC.
My usage on iPad is as follows:
Email
Web internet research
Client data base
Form design and Implementation to PDF
GTD (get things done to do reminders and workflow)
Secure password data base storage cross platform synch
PDF forms with signature
PDF manuals - reading and modification.
Remote access to servers
Time logging for billing
PDF scanning to edit and archive.
Word and excel editing
Navigation
Photo editing
Reading books leisure and business
I.T diagnostic tools.
And much more....