5.10.0 is over a year old and presumably ready for use in Production.

The age just means that most CPAN modules now work with perl-5.10.0, not that 5.10.0 got better in any respect.

Although there are many bugfixes in the branch for 5.10.1, IMHO 5.10.0 is very usable, and it's what most linux distributions ship by default these days (including the upcoming Debian Lenny).

Upgrading to 5.8.9 and then later on to some version of 5.10 feels like a wast of resources to me, so if you plan to do any upgrade that might break binary compatiblity, pick 5.10 now.