If you're planning to buy an iPad for work, you may be in for some disappointment. As it stands, the iPad has no file browser or native printing support. This omission may be a nonissue for some people, but for others--particularly those using the iPad in a business environment--it can be a serious hassle.
Some iPad apps do allow you to print and share files from your iPad, but these tools come with serious caveats. Let's take a look.
Out of the box, all documents that you create on the iPad (or sync to your iPad from your PC or Mac by using iTunes) reside in their respective iPad apps, as there is no centralized file browser. E-mail attachments live within the Mail app. Pictures live within the Photos app. Text documents live within the Notes app. And so on.
Sharing via iTunes
If you have the iWork apps installed on your iPad, you have a few options for exporting documents from the device: You can e-mail them to or from your iPad, share them using Apple's iWork.com service (more on that in a moment), or use Pages' Export feature to access them via iTunes.
Pages' Export feature is kludgy at best. To access the File Sharing pane in iTunes (where you can save files from your iPad onto your computer, and vice versa), you must connect your iPad to your computer, use your mouse to click on the iPad in Tunes' source list, and click the Apps tab. You'll then need to scroll down to get to the File Sharing pane.
This feature is important enough that it ought to have its own tab in iTunes, but instead it's virtually buried in the menus. Also, you can't use this method to automatically sync the contents of a folder on your computer with your iPad, so you're stuck managing files individually.
iWork.com is Apple's service for sharing iWork documents online. It's currently in beta and free for iWork users, but it may become a paid service when it reaches its final form. You can share any iWork file saved on your iPad via iWork.com, where you can view the documents or download them to your computer (you have the option of downloading a Microsoft Office-formatted version of the files, too).
You can also use iWork.com to download files onto your iPad. To do this, launch Safari on your iPad, browse to iWork.com on your iPad, and sign in. From there, tap the blue download icon (a downward-pointing arrow in a blue circle), and tap the appropriate name of the iWork app (Numbers, Pages, or Keynote) from the drop-down list. The document will then open in Safari, where you can tap 'Open in <iWork app name>' in the translucent overlay toolbar (you may need to tap the document in order for the toolbar to appear). Numbers will open and import the file, making it accessible from your iPad.
This method of uploading documents to iWork.com has one pitfall: It requires you to use either an iPad or a Mac running iWork, so the pool of possible contributors with whom you can share will be limited.
A number of third-party apps for iPad will let you share files between your computer and your iPad. These generally work over the air, syncing files via an outside Website or over your Wi-Fi network.
You install the app on your iPad, and a helper utility on your PC, and then you specify which folder of your computer you'd like to access from your iPad. I looked at one particular app, called Print n Share ($7; iTunes link), which lets you, well, print and share your documents.
With Print n Share, you can share the contents of a folder on your PC to your iPad over a Wi-Fi network. You can browse the files from your computer and then copy them over to your iPad, and in many cases you can view them inline in the Print n Share app. But there's no way for your other iPad apps to access the files that you grab via Print n Share.
To test this, I used Print n Share to copy a Numbers spreadsheet and a Pages document from my Mac to my iPad--and I found that I couldn't view or edit either document in the iPad apps.
Though I can e-mail a Numbers or Excel document to myself, view it in Mail on iPad, and then open it in Numbers for iPad, I can't do the same between Print n Share and Numbers. It isn't yet clear to me whether this is a limitation of the operating system and Apple is using some secret sauce to get it to work, or whether iPad app developers haven't yet discovered this particular capability of the OS.
Print n Share recognized the printers I set up to work with my MacBook over the office Wi-Fi network, but if your printer is part of a network domain, you may be out of luck.
Right now, unless you want to sync with your computer, e-mail content to yourself, or upload to iWork.com every time you need to access a document, your best bet may be to use an online document service such as Google Docs. The Google Docs Web interface doesn't yet work properly with the iPad, but Office2 Pro ($8; iTunes link) will let you read and edit your Google Docs, and access any files stored on a WebDAV server such as Apple's iDisk service (part of MobileMe).
Right now, document handling on the iPad is incomplete at best, and nearly unusable at worst. The fact that you have to use different methods to access files depending on what app they were created in is frustrating--and for some users it could be a real impediment to productivity. The iPad may not need a file system as sophisticated as the one on your PC, but a central repository where you could gather all of your documents and mail attachments would be a welcome addition. The task of creating a more seamless solution is likely fall to third-party developers.