I had my blog, before we stopped paying for hosting and lost the content, set up so I could easily post in the following way, more or less.
1. Twitter Tools Plug-In set up to post our new articles to Twitter.
2. Add a new post with the current date.
3. The post is created, and the address bar for the post would have the date-type permalink (/month/date/t-i-t-l-e)
4. I update the published date for the article to a prior date. (The blog is for my friend's numerous videos and such, and he is insistent I use the date they were posted.)
5. The j.mp link generated by Twitter Tools STILL WORKS, so Twitter links stay valid.
How I have it now, Twitter Tools still does not tweet back-dated articles. But if I change the date of an article, it breaks the j.mp link (which points to a /date/month/what-ever permalink). I would use just p=## permalinks, but I thought that was bad for SEO and such.
I don't remember how I did it before, but I remember there being p=## links 'internally' (on the back end), but /date/month/what-ever links when you browsed to the page. At least...I think I remember that. I'm sure it was one of the SEO plug-ins I was using, but I can't remember which one specifically it was. (Right now, I'm using SEO Ultimate)
Essentially, right now, in order to keep Twitter up-to-date and Twitter Tools j.mp links valid, I have to post with the back date, then manually create a j.mp link, then manually tweet the article. I have about 200 Videos to go. Gotta be an easier way!