Amazon.com recently added the ability for us to quickly and easily post affiliate links to products to our Twitter stream (or any microblog for that matter). While I think this is a great development, it also brings a question to mind: how do you disclose that a link is an Amazon.com affiliate link when you're limited to only 140 characters per post? Those who don't disclose--especially individuals like Robert Scoble who have thousands of followers and the potential to influence purchases--could see a backlash.

My plan for my own Twitter stream is to only post affiliate links to products that I have used and recommend or that I think I would like. Additionally, I plan to add links somewhat sparingly and in the general context of the things that interest me and my followers I certainly do not want my Twitter stream to seem like spam!

Here are some ideas for disclosure:

• Include a blanket disclosure in your profile (may be hard to fit since profile also limited to 160 characters!).
  
• Include a hashtag or something similar in each post with an affiliate link: examples: #ad, #sponsor, [ad], #affiliate, etc.
  
• Always precede or follow-up with a disclosure post. This is somewhat clumsy and repetitive.
• Don't bother with disclosure at all.
  

What do you think? Is disclosure necessary? Always or only under certain conditions? What is the best way to disclose?