Probably, yes. It would need to be fully browser-based though. I wouldn't be okay with shipping all of my viewing history to you for it to work.
It would be most useful if it could integrate with my Instapaper workflow. If I visit a page and then hit "read later", that shouldn't be marked read in Google Reader until I've archived or deleted it in Instapaper. Similarly, it would be great if marking something read in Google Reader would archive any matching items in my Instapaper account (this might be way beyond the scope of what you're talking about though).
I would be okay with sharing my Instapaper username/password to make that integration work.
It would be most useful if it could integrate with my Instapaper workflow. If I visit a page and then hit "read later", that shouldn't be marked read in Google Reader until I've archived or deleted it in Instapaper. Similarly, it would be great if marking something read in Google Reader would archive any matching items in my Instapaper account (this might be way beyond the scope of what you're talking about though).
I would be okay with sharing my Instapaper username/password to make that integration work.