Working from the iPad

The biggest issue with working from the iPad is network connectivity; if you are not traveling in a world with ubiquitous wireless access you are going to need a telco with great 3G coverage. In Australia this tends to mean you are going to need a Telstra Pre-Paid micro-SIM for Apple iPad.

Security

Add a password Settings > General > Passcode Lock
Enable Find my iPad

Physical Protection
There are as many options in this area as the market as there are tastes in clothing. The basic physical protection devices you will want to investigate are;

A cover or case
A screen protector

Office Productivity
The starting point for Office Productivity applications on the iPad are the Apple iWork apps; namely Pages, Numbers and Keynote.

The iOS bundled Mail application is ok for email on the road, the applications listed above allow it to handle the MS Office attachments. (UNIMELB: iPhone Exchange email connection and configuration [PDF]). That said, I am looking for a more powerful mail client, especially with respect to dealing with hundreds of mail folders.
Mail

For some extra functionality Quick Office, GoDocs (if you use Google Docs) and Good Reader are worth a look;

For transferring documents between the iPad and your desktop, Dropbox appears to be the way to go;

Social Networking
Twitter, Facebook, LinkedIn, Tumblr et al all have their own iOS apps.

I find that I am using MyPad+ for Facebook as this gives a better experience on the iPad (I am still using the Facebook app on the iPhone).

Blogging: WordPress is my platform of choice, and there is a handy app available.

Power
Without power an iPad is a very expensive paper weight, you will need a strategy to stay charged and ready for work. There are many after market power options available.
I carry;

a Kensington Mini Battery Pack and Charger for iPhone and iPod,
a Power Traveller Solar Monkey & Nut
a 12V cigarette lighter to USB adaptor. This is a worthwhile addition to your kit if you are a road warrior and need to recharge in the car.

Video Out
If you are using your iPad for presentations you will need a method of connecting to the projectors or screens once you are on-site. Generally you will need a VGA adaptor but with many locations now using large LCD screens the HDMI adaptor may also be useful.