I'm going to be upgrading my blog from Wordpress 1.2 to Wordpress 1.5, and I'm expecting to attain new levels of awesome with this new version of Wordpress. First of all, can anyone say "comment spam filtering"? It's frustrating to have to jump through hoops just to block the comment spam I currently get. If you're not sure what comment spam looks like, or how much my site would otherwise be getting, trust me. I would link to an example on another blog where they don't filter anything, but that won't be necessary. It's basically hundreds of sexually explicit comments for every single blog entry.
Second of all, I'm hoping that there are bug fixes that will allow me to use software called Drivel to post without ever having to open a browser window. I would really enjoy not having to actually use my website in order to update it. If you're using Blogger or LiveJournal, or a site like Blogsome or Blogthing (which themselves use Wordpress 1.5!), it's possible to download software in order to post to your blog. You can find and download recommended software from Blogger's page or LiveJournal's page. For all the Xanga people...you're out of luck, because Xanga doesn't offer this functionality (yeah, big surprise there).
All that to say, be on the lookout for big changes.