The currently stable version (3.1.7) of Tunnelblick would cause a kernel panic in Mac Lion while a connection is being made. Workaround is to use a beta version (3.2beta28) which is available at http://code.google.com/p/tunnelblick/downloads/detail?name=Tunnelblick_3.2beta28.dmg, released 7/31/2011.
[Edit 8/18/2011] Just updated Lion to 10.7.1 last night and version 3.2beta28 seems to be unstable as well. It has caused kernel panic two times in a row.
Need to keep looking for a version that works. Did a re-installation of the same version and it works afterwards.