TheMadScientist - 11:16 pm on Mar 12, 2011 (gmt 0)
Sorry for the double post, it's turning into 'thing' for me lately, but I know I don't always go back and read updates to posts, so I thought it might be best to post a separate one for those who already read the previous one:
If you have a secondary twitter account, say for 'new page additions', one that's not intended to attract a large number of followers or one where you let people know the pages will be accessible 10 to 30 seconds after tweeting, you can use that account and the mod_rewrite in this thread: Getting GoogleBot to Spider a Page Now, Before It's Scraped [webmasterworld.com] to make sure the first and only visitor to the page is GoogleBot, then after it gets spidered (the longest I've had to wait in testing is 45 seconds or so) you can pull the block down.
You could even use your main account with:
Check out my new page, it's going live for you to visit in 1 minute: http://example.com/the-page ...
This way, you let people know they can't get in to it yet within the tweet, so they won't be surprised if they get an error when they click on the link 'the second' it's tweeted.