Since the most recent 2.4 UML patch seems to have some issues that are still being worked out, I've decided to build a 2.4.27 version of the very stable linode31 kernel. This is essentially the same as 2.4.26-linode31-1um, but brings us up to date with the latest kernel sources. Included are MPPE support, and kernel crypto stuff...
How to Upgrade
See if you're already running 2.4.27-linode34-1um by viewing the output of "uname -a" inside your Linode. If not, follow this procedure:

Log into the Linode Platform Manager (LPM)

Configuration Profiles --> Click on your configuration profile

Make sure the Kernel drop-down has "
Latest 2.4 Series" selected and Save

Reboot your Linode
Thanks and enjoy!
-Chris