Make posts page show excerpts()

if ( is_home() || is_archive() || is_search() ) :

the conditional statement occurs more than once in loop.php – have you edited it all?

btw: this question has been answered before and should be found using forum search.

This doesn’t work for me, I’m using a static page so I also tried is_front_page()?

I’m using a page called ‘Our Blog’ as my posts page.

should make no difference;

the conditional tag is_home() refers to the posts page:

http://codex.wordpress.org/Function_Reference/is_home
http://codex.wordpress.org/Conditional_Tags#The_Main_Page

alternatively, you can edit this whole section:

<?php if ( is_archive() || is_search() ) : // Only display excerpts for archives and search. ?>
			<div class="entry-summary">
				<?php the_excerpt(); ?>
			</div><!-- .entry-summary -->
	<?php else : ?>
			<div class="entry-content">
				<?php the_content( __( 'Continue reading <span class="meta-nav">&rarr;</span>', 'twentyten' ) ); ?>
				<?php wp_link_pages( array( 'before' => '<div class="page-link">' . __( 'Pages:', 'twentyten' ), 'after' => '</div>' ) ); ?>
			</div><!-- .entry-content -->
	<?php endif; ?>

and change it to:

<div class="entry-summary">
				<?php the_excerpt(); ?>
			</div><!-- .entry-summary -->

again, make sure to find and edit all occurrances in loop.php

YOu can use <?php if( is_page('5') ) { ?> instead of is_home() ; Replace 5 with your page id which you are using for showing post. I am sure you may have found the solution, but I think it would be helpful for someone else also.