I feel that it is especially helpful if your product's webpage has a single paragraph, no longer than 1,000 characters, describing the product. Not only is it helpful and simple for a new customer to find out about your product, it fits perfectly in Delicious's notes. I do a lot of bookmarking and I'm really lazy. More often than not, I'll copy a chunk of text from the site I'm bookmarking for the Notes box instead of writing my own. This gives me and my readers instant appreciation of the newly bookmarked product. Here are two lovely examples of product sites that have got this spot on:
Boxee has a 233 character Delicious paragraph

Drop.io has a 231 character Delicious paragraph
This is how it fits in Delicious: Having your site bookmarked on Delicious is important. Having it appreciated by those sharing it is priceless.