Yes, but it takes a small bit of work. Each post has its own post 'number' which you can see right before the date of the particular post (for example, the post number for your post starting this thread is #198705).

If you click on a post from the main forum page, you'll see the URL change for that post, and will look something like: http://www.backpacking.net/forum/ubbthreads.php?ubb=showflat&Number=198682#Post198682

If you sent that to someone, they would click on it and go directly to that post. If it's the first post in the thread, it would also, of course, lead them to that thread.

But what if it's an old post and not a new post clickable from the main forum page?

Just use the same line as above, but substitute the post number with the post number of the post you want to direct someone to in both places (ie, 198682#Post198682 would become 198705#Post198705).

Hope that all makes sense.