Question about gadget blog

Hi,
I have a question. Let`s say I have a smartphone review blog.
I want to make an article about Sony Xpire S3 (not released yet).
In this article I will wright about release date, how much it`ll cost etc.
After the release of X3 my article will be outdated because nobody want to read
about the release date if it?s already on market.

What is better?

1. Write a new article and 301 redirect the old article to the new
2. Edit the article (rewrite)
3. Update the article with fresh content (add new content)

anyone?

Just update the existing indexed article with new data. You will get the benefit of indexing th article before others. But I suggest put some upcoming quarry keywords in the article so that it can be indexed for the important keywords before the original phone releases.