Some users have reported that they are unable to install the $20 iPod Touch "January Software Upgrade", which is supposed to place Mail, Google Maps, Notes, Weather and Stocks applications on the Touch. In most cases, users are able to upgrade successfully to iPod Touch firmware 1.1.3 (required to get the new apps), then click the "Buy Now" button to purchase the Software Upgrade. After performing the post-purchase sync (as directed by Apple), however, the new applications do not appear on the iPod Touch -- even after a restart. Worst of all, repeated attempts at purchasing the software result in multiple credit card charges.
The fix for this issue is simple: restore your iPod Touch using the "Restore" button in iTunes. When prompted, do not restore your iPod Touch from backup. For most users, this has resulted in an immediate appearance of the new applications. Note that any media will need to be re-synced with your iPod Touch.
If you're having trouble restoring your iPod Touch, see this Apple Knowledge Base article.