The 'Search this site' form should be preceded by a header for accessibility. D7 has the search_theme_form enabled by default in the left sidebar but with no header. The block version of the search form, search_block_form, already gets a visible h2 header called "Search". But the block one is not enabled by default. The search_theme_form is the one used by default and it is less accessible.
The only way for a screenreader user to find the search_theme_form is to find a text field and submit button. It is better to provide an h2 header so screenreader users could jump to or skip over the site search just like they do with the navigation bars. Although it is not required by WCAG 2.0, the site search form should have a preceding h2 header because it is a key navigational tool just like navigation bars. Many sites add such a header above search as a best practice.
ARIA also provides a landmark role for search.
|PASSED: [[SimpleTest]]: [MySQL] 20,595 pass(es).|
|PASSED: [[SimpleTest]]: [MySQL] 20,459 pass(es).|
|#37||search-theme-form-heading-1.patch||585 bytes||Everett Zufelt|
|Failed: Failed to apply patch.|
|#34||search-block-form-heading-1.patch||573 bytes||Everett Zufelt|
|Passed: 13237 passes, 0 fails, 0 exceptions|
|Passed: 13281 passes, 0 fails, 0 exceptions|