The Toptal.com site has an interesting post mostly relevant to those out there that straddle the line between design and development. It wonders how much coding should a designer know to get the job done.

Many designers think each discipline should mind their own business, while others see no problem in professionals wearing multiple hats. Many developers see designers who code as a threat, while others see it as a facilitator. This is a hotly debated subject, and although I think some great designers are also superb at coding, I will always defend that the more you focus on a particular area the best you will be at it. But this shouldn’t be a reason for you to miss out on the benefits of having another skill under your belt.

The article then breaks down the benefits of designers learning to code by levels of knowledge:

• Step 1: Know the basics of HTML and CSS
• Step 2: Front-end JavaScript and AJAX could make you a unique asset
• Step 3: Back-end JavaScript might be overkill
• Step 4: Database Architecture and Software Engineering Won’t Get Designers Anywhere

For each point there's a brief explanation of the level of knowledge it represents and what he sees as a general designers attitude towards it.