Yes hardly 15 days ago Wordpress 2.6 was launched !! I upgraded to it. Working fine for me. I didn’t notice any flaws but still tester are the great people. they do great things with there box.
Few Major Issues observerd :

Sporadic timeout /wp-includes/gettext.php
Category/tag URL changed if the permalink structure has static strings
Publishing [...]

When You blog its essential to tell others that you have updated your blog. Update Service in Wordpress is the Service which helps you to do this.
Update Services process the ping and updates their proprietary indices with your update. Now people browsing sites like Technorati or Sphere can find your most recent posts!!
By default [...]