For those SaSS fans out there checkout compass's CSS3 gradient helpers (http://compass-style.org/docs/reference/compass/css3/gradien...). Compass does not include the dx filters, but that would be an excellent thing for that lib to support.

Also, the markup Posterous uses is more verbose than it needs to be. We figured out a way use plain 'ol <button/> or <a/> tags and style them as buttons. Maybe I'll blog about that when we roll this stuff out.

Visually, those buttons look good.