I'm having a real headache. Using 1.3 alpha-4 (Oct-25 build).
I'm assigning the title of an article (on a single entry page) to a variable outside the loop. Using get_the_title($post)worked fine in 1.2, but in 1.3 fails to return a value. As single_post_title('', FALSE) provides the same functionality, no big deal (for me) here.
I'm doing the same thing with a category (on category page). Again, get_the_category_by_ID($cat) worked in 1.2 but not 1.3. Well, that's not quite correct. It does works in 1.3, but only for one of two installations I'm running. Also, single_cat_title('', FALSE)fails, but again only for one of the two.
Again, they're both running the same 1.3 alpha (and same versions of PHP and MySQL, such as it relates). The only real differences I know of between my 1.3 installs are:
1. Server of version that works is running IIS, one that doesn't is Apache.
2. Version that works is in root folder, one that doesn't is in a subdirectory.