This is an interesting problem. While not possible with the blog module all by itself, you could get somewhat close to what you want with the help of a "helper" module. It would not be perfect and it would also require some rearranging of your blog page and (perhaps) site skin to present things properly.
One Approach:
You could use a "helper" module to query the DB for log entries and then build custom links to those entries. Your custom links would be configured to open in a different target than the host window (open in either a frame or a different browser window). Since it sounds like you want just the blog posting itself to show in a separate area (not the entire web page the blog module is on), you'd need to display just the module itself with a "blank" skin and no container. This is easy to do by leveraging DNN's built-in "print view" functionality.
I've previously posted a simple example of how to use a free "helper" module to query the DB and build custom links to Blog module entries here:
Create a "Most-Commented Blogs" module
http://www.eguanasolutions.com/DNN_Blog/EntryID/13.aspx
For your example you would not use the logic that counts comments but instead just provide the basic blog entry links, adding an appropriate "target" attribute to your link tags to open the links in a different frame or window.
As for showing just the module by itself, you'd need to include your module ID in the link URL in the form of "/mid/{your blog module id here}/" and append the rather long standard DNN "module print" querystring to specify a blank skin and no container. The "module print" querystring to add to your links is:
?SkinSrc=%5bG%5dSkins%2f_default%2fNo+Skin&ContainerSrc=%5bG%5dContainers%2f_default%2fNo+Container
LINK EXAMPLE -- Let's say you have the following:
- A frame or iframe on your web page with the name "showblog". This is where you want the blog entry to appear after clicking a link from a list of blog entry links as provided by your "helper" module.
- A blog module with the module id "125".
- A blog entry with the link http://www.yoursite.com/Default.aspx?tabid=54&EntryID=8
You would want to use your "helper" module to present the user with a blog entry link (a very long link) in the following form:
<a href="http://www.yoursite.com/tabid/54/mid/125/entryid/8/Default.aspx?SkinSrc=%5bG%5dSkins%2f_default%2fNo+Skin&ContainerSrc=%5bG%5dContainers%2f_default%2fNo+Container" target="showblog"> Your blog entry title here </a>
This will show only the blog entry in the target frame (or target browser window).
You would also need to prevent users from browsing directly to your blog module (you only want them to see entries in the target frame when they click a link in your "helper" module). You need to keep the module public, though, so the easy way to hide it from users is to place it on a page and set the page to not be included in the menu. You will also need to consider other aspects like the blog link that are inserted at the top of each blog entry, the blog search module, etc. How intuitive will the various interfaces be (or will they even work at all) in a dual-frame setup?
As I said before, this is not at all a perfect solution but it does get reasonably close to what you described. Hopefully this will give you an idea or two on how to approach your issue.
Good luck!
-mamlin