Tried that several times…
No matter what I tried, a new template would not apply to a posts page. But I got a custom sidebar working instead (with serious professional help).
1) I made a new sidebar called sidebarblog.php which contains the standard blog page stuff (archives etc). Then called it in index.php AND single.php just above the footer (withing the theme folder):
<?php get_sidebarblog();?>
2) Then added this code to general-template.php (in the wp-includeds folder):
function get_sidebarblog() {
if ( file_exists( TEMPLATEPATH . ‘/sidebarblog.php’) )
load_template( TEMPLATEPATH . ‘/sidebarblog.php’);
else
load_template( ABSPATH . ‘wp-content/themes/default/sidebar.php’);
}
My big problem now is that I can’t bring back the date/categories/comments back to the bottom of the posts on my post page without them also appearing on the main pages. Plus the “Blog” list menu item does not have a current state like the other menu items (grrr). Something to do with a page being set as a “posts page” makes customization very difficult.