Amazon just announced a firmware update for the Kindle2. The K2 will finally get PDF support. This update will also include improved battery life. Amazon is claiming 85% longer run time with Whispernet on, but no improvement to the 2 week standby. It sound like they've added a standby mode to the software that manages the connection.
press release
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Update: I went looking for the update and I found
this page. The update also adds to the K2 the ability to rotate the screen. Shiny.
US Kindle update
Int'l. Kindle update
Kindle DX update