different permissions

Yes, I agree.

Create a private vocabulary.

Create a user with a role that has both 'Administer own taxonomy' and 'View private taxonomies' permissions. Log in as that user. Go to admin/structure/taxonomy by appending that in the URL. You will see three links for the private vocabulary. The 'Administer own taxonomy' permission is required to see the first and third links while the link in the middle requires the 'View private taxonomies' permission. If you click on the first link you should just see your terms (I am seeing all the terms which means I probably introduced a bug getting this release out - I will fix it shortly. I am switching this to a bug report for this bug.). If you click on the edit link you should be able to modify that term. Note that Drupal 7 has separate permissions for editing and deleting terms for every vocabulary. You eill need to make sure you have given the role these permissions for this vocabulary in the Taxonomy section of the Permissions page. Drupal 6 does not have these permissions. If you go to the 'view all terms' middle link on the original page then you should see everyone's terms and be able to filter by the user since the number of terms could grow quite large.

Now give your user permission to create content. Go to that content type and add a new field where the type of data is Term reference. Choose the private vocabulary you created in the first step. Note that this procedure is different in Drupal 6 since you go to the taxonomy admin pages to add a vocabulary to content types.

Return to your user. Click on the Add content link in the menu. Select the content type with the term reference field. Scroll down and you should see the field. If you click on the select box you should just see your terms.

There may be things I need to tweak and things I need to add to get everything functioning. Please file issues as you discover any problems.

I hope this explanation helps.

Fixed bug with users with both permissions seeing all terms on the page for adminstering their own terms in 7.x-1.x-dev. Working on a backport to 6.x-1.x-dev.

Fixed in 6.x-1.x-dev.