I have never farmed worms before but I believe I recall that you tend to want a type of worm that will not survive in the "wild" garden. So your releasing the worms into the garden would simply kill them.
I would believe, much like with a pet, you could prep the worms and be able to leave for a couple days without too much concern.
GW has a Forum on vermiculture. Try posting there.
http://forums.gardenweb.com/forums/verm/
Mike

I would think if you are gone for awhile, that if it was moist enough (but not too moist) that even without feeding every day that they could eat the bedding. But I would ask on the vermicomposting forum to be certain.

I'm normally just a lurker on this forum, but i do have a worm farm. I'm not sure how long you're gone when you travel, but worms can go a long time w/o being bothered. I've left mine for at least 2 weeks at a time, but check w/ the wormers on vermicomposting, b/c i'm sure they can go even longer. They seem happiest when left alone anyways.

I've been transient for over three years, having lived in many different locations. I take my worm bin whever I go. It's been outside under a tree, on two different balconies, in a closet, in a hallway, and outside my trailer. I've never replaced my worms since the first batch I bought nearly 4 years ago. I've left them for long periods of time, (like a month). They need very very little care. Just make sure they don't fry in the sun or run out of food in warm weather when they're extra active. make sure there's plenty of bedding (I use newspaper sometimes I don't even shred it.) It's always best to shred food and newspaper, but often I won't shred either, and the worms are just fine. There are always avocado shells in my bin, too, as they break down very slowly. I think the worms like having these in there, but I don't know for sure.

And, no, don't let them go, they will most likely die in a "wild situation" although I can often find them underneath my potted plants after having escaped from the bin.

if you do go away for a while, just put in a lot of food (not a ridiculous amount) and bedding (I think newspaper works the best) and they'll be happy as can be while your'e gone.
hope this helps!

they seem to love the paper towel rolls, i try to tear them open so they dont just clump up. they'll do just fine for weeks provided you give them food. they will smell like the dickens if you get them too wet tho!