Where are the tomatoes position in relation to your other plants in terms of direction? The general advice is to place taller plants to the North of shorter plants so the taller ones don't shade out the smaller ones. I have all my tall and trellised plants on the north edge of my beds so they won't block the sun for the other stuff.

Here is a link that might be useful: Luke's SF Victory Garden

My Northern most row is Corn which is about chest high. The next row is Tomatoes which are a few feet high.
The next ros is another row of tomatoes which are only about a foot and a half high (they were started later).
The next and southern most row is herbs. The herbs are getting sun but some of the tomato branches are extending out over the top of the herbs shading them. I would only be pinching back about six inches of the southernly extendign branches.

gmreeves - Here's a publication from the Alabama Extension System concerning pruning of tomatoes.

EG

Here is a link that might be useful: ANR-1156

Thanks for the article EG. I went ahead and clipped the long branches back that I was concerned about even though I have yet to find an answer to the actual question of whether it is o.k. to do this. I guess I will find out by the way of trial and error. I have already pruned the branches up the first set of flowers on all of my plants as stated in the article. We will see what happens to the branch that I pinched the end off of.