According to readers that have reported in, Sprint has issued PRL 60610. It is not known what Sprint has changed in this revision, however Sprint suggests all users update to the latest PRL.
PRL 60610 is only for EV-DO Sprint devices that support roaming triangle. Only phones with a PRL of 60000 need this update. Sprint will be pushing this update to phones, but in case you want to get the update manually, call data support and ask for your account to be flagged for update.
The PRL file has become increasingly important to keep up-to-date, as it has now grown to support features such as EV-DO data roaming. Most customers do not need to do anything, Sprint will push this PRL update to phones automatically.