The problem exists, at least for me. I even see it happening here. Someone posts a link to 5000 word blog entry and then posts a comment about whihc bits are interesting. This might be good improvement on signal to noise ratio.

If they can add more features to this, like pinned comment notes on a web page, they can find a demand from web designers as well.

i would also disagree. this problem exists, but most people work around it. i often see legal/compliance feedback on customer facing web pages. they'll either copy/paste the text of concern into an email and make comments (which are now out of context design/layout-wise), snap screenshots and draw on them in paint (arts and crafts fun!)... something like this might make more sense in some cases.

it's a way to virtually stand at someone else's monitor and point at stuff.

1. why just highlight? why not a basic set of drawing tools? (solve the screenshot issue. i'd rater go to a url than get a giant html email.) ...hell, animated overlays, watch me gesture with a mouse... getting into screen capture apps, i know.

2. gotta work better in IE. i could see this being popular in a business/corporate setting, but you are largely dealing with IE there.

neat idea.