No need for the $post global in _s_scripts()

The wp_attachment_is_image() function will figure out the $post global internally, does not require one to be passed. Makes _s_scripts look cleaner.
Improve code readability in no-results.php

It's difficult to get around php if () {} statements when mixed with markup, so using if () : endif; syntax instead.
Adding current search query to searchform.php

It may be useful to display what the user searched for in the search input, especially on pages like no-results.php where the search query is not displayed anywhere.
No need for the_post and rewind_posts in author archives.

We can get all the information we need about the author by using get_queried_object within is_author.
Merge pull request #34 from kovshenin/patch-3

Improve code readability in no-results.php: "It's difficult to get around php if () {} statements when mixed with markup, so using if () : endif; syntax instead."
Merge pull request #35 from kovshenin/patch-4

Adding current search query to searchform.php
Don't print markup in _s_content_nav() when it is not needed. Fixes #28.

Added checks for previous (or parent) and next post in _s_content_nav() before printing any navigation-specific markup. Same approach for when using the function to print pagination links on a posts set for less than two pages.
updated the styles for the buttons, switching from using background css gradients to using box-shadow techniques
Merge pull request #32 from kovshenin/patch-1

Stop passing global $post->ID to wp_attachment_is_image() in _s_scripts() - It is not needed. fixes #32. props @kovshenin.
No need to rewind posts if nothing has been queued up yet
Merge pull request #53 from joshbetz/patch-1

Remove unneeded call to rewind_posts() props joshbetz
Fix typo in readme.txt
Update the HTML "class"  system

Improving on the naming convention of our classes with consistency
adjustments. Also creates a better hierarchy (matched pairs) for them.
Update the main stylesheet to use the available classes

Avoid polluting the CSS specificity landscape with ids if we have
suitable classes
Merge pull request #54 from joshbetz/patch-typo-1

Stop dancing the "Can-can" in readme.txt. s/can can/can. props @joshbetz. Fixes #47
Correct use of get_queried_object() for author archives.

The ->data object (used previously) stores the author data, but the WP_User class has the __get magic method that grants access to that data, so using get_queried_object() without ->data is correct, and compatible with 3.2, which does not use magic methods. Also url-escapes get_author_posts_url.
s/double/single quotes in register_sidebar args array.

This is probably left over from a time when there was a line break
following the HTML tag.
Merge pull request #36 from kovshenin/patch-5

Use get_queried_object(); to retrieve author data in archive.php. This removes the need for the_post() and rewind_posts(). props @kovshenin fixes #36
Add todo tags to the DocBlocks of functions that contain backward compatibility with previous versions of WordPress stating when back compat should be removed. _s supports the current stable version of WordPress as well as two prior major releases.
Updated read me.txt to include information about http://underscores.me