You might also consider adding some kind of deep handle or such on the sides to make it appear more like an island. A cool place to hang a dish cloth or utensils. The butcher block part is easy. Try: http://www.johnboos.com/ or the link below. I've seen both on these products on this site and they are pricey but gorgeous. The Grothouse Lumber stuff is off the scale. If you need to be more budget concious; I've seen people who have had very nice results with the butcher block tops from IKEA. I don't know much about casters but I'm sure you can look online.

Here is a link that might be useful: Grothouse lumber

Sounds like a great plan to me! Mockett has some super zippy casters with brakes.

And of course there's the appropriately named coolcasters.com, including wooden versions that might look rather nice.

No advice other than to echo what's been said. I think that's an awesome idea. Be sure to post pics once it's done!

Don't forget to check eBay for butcher block.

(The seller will do custom sizes.)

Here is a link that might be useful: Butcher Block

This could be wonderful, and I'm looking forward to seeing pics! Since this will be completely custom, you can add all sorts of features. Remodelfla mentioned adding a towel bar. You could also add a knife rack. Another idea is to add a bookshelf to one of the other sides before adding the beadboard skin to make it rectangular and gain more storage underneath. Wine bottle cubbies would be cool, as well. Google terms like "kitchen island" or "rolling kitchen cart" and look at all the commercially available ones to get ideas for fun features to add.

Keep in mind, however, that the height of this cabinet could be substantially taller than your other cabinets. With the added height of the casters and a butcher block top (I'm picturing a thick top looking best), there could be as much as six or eight inches difference between this piece and your perimeter counters. If you're tall, you might like having the raised area for chopping, but it's certainly something to consider. If you don't want the extra height, depending on how the cabinet box is constructed, perhaps the toekick section of the cabinet could be removed to make it less of a difference.

I saw this exact project on HGTV just the other day - can't remember which show. They were doing a tiny kitchen and made a portable island out of a cabinet... check out their web site. They might have hints. Great idea!

if you need to compensate for height: perhaps you can cut odd the toe-kick section at the bottom.

After all, the casters should be attached to the bottom of the cabinet itself, not tot he sides (you may need to make a platform to join the two of them).

Yes, I'd definitely cut off the toekick section to give you stability and room for casters. My carpenter did this to my cabs in about 5 minutes flat (we were putting new bases with legs on), it's easy if you have a jigsaw or portable saw with a straight-edge guide.

I'm really digging those wooden casters with brakes I linked earlier, come to think of it. Excellent price, too. 4 of 'em hold over 500lbs, which seems like a decent amount of cookbooks or wine bottles.

Hmmmm... *project scheming light goes on*