Backgrounder by Lance Fetters (ashikase) has been updated to support iOS 4.2.1
Backgrounder allows for total control of backgrounding on an iPhone/iOS-based device. With Backgrounder, *you* decide when an app should keep running, and when it should quit.

Backgrounder provides true backgrounding; minimized apps can be made to continue to run as if they were still the foreground app.

What’s New In This Version:
? Updated for iOS 4.2.1.
? Changed method used for preventing installation on unsupported iOS versions.
? Changed version numbering due to move from Google Code (svn) to GitHub (git).
You can download Backgrounder from the BigBoss Cydia Repository.