The V8 that ships with node 0.4.x uses an unsophisticated method of seeding its random number generator- it simply uses the current time in ms. Worse, that version of V8 (at least) doesn't provide a way to explicitly reseed the RNG.
In situations where multiple processes can spawn in the same ms, processes can be seeded with the same value, leading to bad problems like UUID collisions. When using the 'cluster' module, it's quite easy to observe this behavior.
This plugin uses David Bao's reseed.js (see http://davidbau.com/archives/2010/01/30/random_seeds_coded_hints_and_quintillions.html) to provide a reseedable Math.random(), and hooks the init_child event to reseed the RNG with a sligtly better seed at spawned-process startup time.
All users of the 'cluster' module should consider using this plugin.