Listing Archives By Author and Category

I’m writing a theme for a new WordPress blog. It’s a multi-author & multi-category blog. In general, it will be seen only by author or by category. Essentially, I’m faking multiple-blogs with a single installation of WordPress because every author’s post will be displayed on their author page, which will appear to be their own blog.

When one is looking at an author page, I’d like to display a list of that author’s archives, linked by month. So, if I were viewing Bob’s blog, the monthly archives list in the sidebar would link to a month’s worth of his posts, and his posts only, instead of showing everyone’s posts in that month.

I’d also like to do the equivalent for categories (a list of monthly archives within the current category).

Is this doable?

Thanks!