A team of developers consisting mainly of caj2008 and unixpsycho from PreCentral-Forums managed to overclock the Pre, now running 800MHz stable.
Currently this requires a custom modified kernel. caj2008 and unixpsycho released a kernel for webOS 22.214.171.124, a kernel for webOS 1.4 is still under development. Anyway you may check this vid: webOS unbelievable fast.
Kudos to caj2008 and unixpsycho.