Categories on separate domain?

Long time lurker, first time poster.

I run a blog that is expanding. We are going from one blog to three.

I’m wondering if it’s possible (without moving to WordPress MU) to have a page or two that appear to the end-user as a separate blog with its own domain? – but is simply a category under the main blog.

Example: WordPress is installed on Domain1.com. The main flow of posts on Domain1.com. Posts with the category of ‘photo’ appear on another page, which is under Domain2.com. In reality I’d do this for ‘articles’ under Domain3.com as well.

Am I asking for something that’s technically impossible? I’d really love to avoid moving to WordPress MU, the conversion process seems difficult at best.

Ultimately, the three blogs are only going to be loosely related under the same organization umbrella. They’ll each have their own unique brand. Just hoping I can use the same wordpress backend to run all 3 because they’ll be maintained by the same people and at times posts will cross over.

I had a look at the ‘multiple blogs’ post and it didn’t seem to answer what I need to do.

Thanks for your thoughts