This is a problem that I'm guessing many of us have - how to keep track of miscellaneous comments you make on someone else's blog, to check for follow-ups? With Newsgator and Outlook 2003, one way to help with this scenario (I admit, it's not a perfect end-to-end solution) is to use a custom flag toolbar and search folders:
1. Add the custom flag toolbar and name one of the flags “I Commented“, or “BlogComment“ or whatnot
2. When you are reading an item and click on the link to see the comments online, after you add your comment, go back and flag the item in Outlook
3. Create a search folder that looks for items in your feed folder tree with that flag set (on the “More Choices“ tab, choose “Only items which: have a [color] flag“)
4. Right click on the search folder and add to favorites
Of course, this only works for comments on blogs to which you've already subscribed, but it will at least give you a quick entrypoint to those posts so that you can periodically go back and click on the links to check for any updated comments. When you decide you don't want to track that comment thread anymore, you can clear the flag on that item while viewing it in the search folder, or just delete the item.
Such a system can also be used for marking which posts you want to point at in your blog. Scoble mentioned a while back that he drags items into a different folder for following up, but using search folders and flags wouldn't be as many steps (and would keep the items in their original folders in case that is part of your blogorgizational style).