There's a way to do it now, but it's not real obvious. It would take a vast amount of effort to make it more user-friendly so I'm not gonna try lol.
To find your old posts:
Click on your own name in the member list or in a thread so your User Profile pops up. You'll see some statistics on your total posts, and a small link saying search user posts. Click on it and you'll get a list, with a search box available if you want to look for something specific.
Here's a direct link to yours:
memberlist.php?mode=viewprofile&u=4393Alternatively, you can go into your user control panel and click on overview. There's a "show your posts" link under the activity heading. But the way this option displays is a lot different than the previous technique, and might not be as satisfactory.