A common question that's increasing in frequency lately is "can I use my iPad/Xoom/Galaxy/etc. tablet for field work in photography"? I'll have a longer article on iPad use for photography soon complete with application suggestions, but the answer to the question is usually another question: "how much do you like to live on the (b)leading edge"?
Let's turn things around for a moment and ask ourselves what we would really want from a field device in tablet form: (1) easy ingest with renaming/metadata; (2) convenient tagging/rating; (3) raw conversion; (4) basic editing functions (cropping, modest corrections, cloning, etc.); (5) output to any size and anyplace through both wired and unwired capabilities of the tablet.; (6) alignment with our desktop image systems (e.g. Lightroom, Aperture) or Web systems (e.g. Flickr).
The first five things sound like Lightroom iOS or Aperture for iPad. Both referenced products are currently very sophisticated and large scale desktop applications that do all those tasks well. The problems we run into with those five tasks on a tablet are: no file system (iPad, though iCloud might come to the rescue) or no common ingest system (others), no monitor calibration, no raw support by the system OS itself, not enough internal memory available to the CPU for large image processing, and often a lack of applications that do exactly what we want. Yes, you can actually scrape by with an iPad to do what the original question suggests, but you'll end up with a hodge-podge of applications and a convoluted workflow, and it won't be particularly fast. On other tablets, the answer is currently a bit worse: some of the apps you'd want either don't yet do all the tasks you'd want them to, or don't even yet exist for your tablet. But even where they do, you end up with many of the same problems you have on the iPad. With Android, the UI keeps changing, too, which is a bit intimidating to consider.
To put it succinctly: it's still early in tablets. It took eight years into the DSLR age before we got Lightroom. And even then it didn't fully solve all our problems. We're going to go through a similar thing with software on tablets, too. That said, the two things that I think are the big bottlenecks for really using a tablet in the field for everything are lack of easy monitor calibration and lack of memory available to the CPU. The former means that you have to be careful about making changes based upon visual examination while the latter means that performance on large image files will be slow at best.
We'll get there eventually, but right now someone attempting to do a full workflow on a tablet is going to be a pioneer, and like all pioneers needs to be ready for any and everything. Things will break, things will change, some things can't be done easily or at all, some things aren't worth the time and energy you put into them. You only need to compare a tablet against an 11" MacBook Air these days to see just how far the tablets still have to go. They'll get there, no doubt, but they're a long ways from where we'd need them to be.
So I'll use the Magic 8-ball answer: "Ask again later."