Solaris's version of sed does not support the -i (in-place) option. You could create a nasty script that does all the intermediate saving for you, but I chose to go a different route ... perl.
Perl has some options that can be passed to it which allow it to function on sed scripts. If you are deploying your Rails application to a Solaris environment, you can use this Capistrano task instead:
My stats should hopefully be a bit more relevant with this little gem.