We are remodeling our kitchen/dining room area and the walls are plaster with no insulation behind them. While we're in the mess, we want to insulate, but do not want to tear down plaster from walls, insulate, then replaster or or drywall. Can we poke holes in plaster and blow in insulation? What are our options?

There are options. Open your phone book and look under insulation contractors. There are too many pros and cons to type with my tired fingers. A professional company will be liscenced and certified by any number of industry organizations.
List your pros and cons. Price vs. authenticity, speed vs. product longevity. Ask the right questions and you will get the right answer. A professional contractors should help you with your costs vs. values analasys. Quality/service/longevity vs. budget.
Personally, in my home I would not skimp on the insulation.

There is no good way to place insulation in a wall by blowing anything in. The problems are that whatever is blown in may not completely fill the cavity, because of blocking in the wall or utilities or other obstructions, and it may settle after installation, leaving the top of the wall still uninsulated. Then there is the question of a vapor retarder, which will not be present, so when dampness inevitably invades the wall cavity, the insulating value of whatever was blown in is reduced to almost zero. This is especially critical in a kitchen, where much moisture is produced in great quantity.

I usually counsel my clients with houses such as yours to pay attention to every other detail first...insulation in the roof;/ceiling, caulking and sealing all openings, and such, and worry about the walls last, if ever.

Simply blowing in some insulation could mean that moisture will be retained in the insulation, possibly leading to problems of mold growth and wood rot within the wall.

I would check with an insulation contractor in your area first. Having said that, blow in cellulose should not be a problem. You can run a stud finder on deep scan to find any blocking, I doubt that you will find any in a turn-of-the-century home, but you may if it's newer. Drill fill holes at the top and bottom of the wall through the plaster. The bottom ones are to verify that the insulation is filling the wall. If you run into blocking, drill below it and fill from there. Strip off anything on the wall that is not firm clean paint i.e., cabinets, wallpaper, door and window trim, loose paint and dirt. Patch all damaged areas, caulk any gaps around opening, then paint all outside walls with two coats of vapor barrier paint (check for the HUD approval label) or if you cannot get vapor barrier paint (try really hard to find it before you substitute) paint on two layers of the best latex paint that you can find. Vermiculite can be substituted for cellulose, but make sure you have all your receptacles in because it will flow out anywhere you poke a hole. An insulation contractor may have better ideas. Good luck!

HERE IS A HEADS UP. I HAVE PLASTER WALLS IN AN OLDER HOME. WHEN I DRILLED INTO THE WALL I DISCOVERED THAT THERE IS AN INNER LAYER OF PLASTER BETWEEN THE EXTERIOR SHEATHING AND THE INTERIOR PLASTER. THE INTERIOR WALL HAS SOLID 1X6 WITH GROOVES TO HOLD THE PLASTER, THEN A COUPLE INCHES IN, THERE IS A FURRING STRIP WITH LATHE AND PLASTER TO CREATE AN "AIR CHAMBER" I ASSUME TO HELP INSULATE.

Don't make any assumptions about older homes. Some have full-depth diagonal bracing in the walls, with the studs stopping and starting below and above the diagonals.

Here are some truths:

Whatever you put in will not have a vapor retarder, and will become damp and lose most of its insulating value, ESPECIALLY in a kitchen.

Whatever you put in is not likely to fill every stud space completely, and is also likely to settle, leaving some part of the top of the wall uninsulated.

Whatever you put in, it will be a long time before you recoup the cost of the installation, if ever.

There are many many steps which are easy to take, that should come before you deal with the walls. Weatherstripping, caulking and sealing, etc., can provide much greater return on your dollars.

Insulate the heck out of the roof/ceilings, seal the house of air leaks, and save your money.

Noone has mentioned foam insulation that doesnot become wet and harbor moisture, nor does it settle over time. I have used the product Icynene and loved what it did for us. Our exterior brick wall was originally erected in 1900 then another brick veneer placed over it in the 80's during a renovation. They had onply bothered to put in new 2X4's and sheetrock. both layers of brick were allowing moisture to come into the wall space from the outside everytime it rained. This foam causes the moisture to sheet away and cannot absorb it. So in our case we had to deal w/ drainage issues eblow, but that won't apply to you. In your case you'd get the 2 in 1 benfits of insulation and vapor (moisture) retarder. You would need to drill 2-3 holes per bay to get a quality fill. Contractors who install this our very accustomed and trained to deal with just your type of situation. Only catch, that I know of, none of the foam products can be installed by homeowners, only professionals.