Here's what I have been using to search for posts by author in lieu of the old method where you could view someone's profile and pull up his/her posts from there. This isn't as good as the old method but it's about as close as I've found via the search engine.
1. Go to "Search"
2. Click on "Advanced Search"
3. In "Search For" box, type in "a e" (leave quotes out)
4. In "by user" box, type in user whose posts you want to find
5. Under "Options", choose "Show results as messages"
6. For "Search Order," choose whatever order you wish to see the posts in.
When you get the search results, all the a's and e's in the posts are highlighted in yellow which is distracting but at least you can sorta kinda get the same function as when you could search an author's post from the profile area.