Konami has annouced it's plans to demonstrate the the next episode for Solid Snake in "Metal Gear Solid 4" at the Tokyo Game Show next month. It is unclear whether this demonstration will just be a rehash of what we saw at E3. However that footage has been widely circulated in Japan, so one would think that Konami would want to have a bit more to show.
"Metal Gear Solid 4" was introduced at this years E3. The next installment will be a departure from the series with regaurd to sneaking around the teaser trailer seems to indicate. "No where to hide" was the teaser's theme, what exactly this means is anyone's guess at this point.
The Tokyo Game Show is scheduled for September 16th-18th.