I am considering mod_gzip for my server but that is not an option for people on hosted servers that are unable to customize the apache installation. However the php compression stuff can be used without having to modify the server configuration.
Pros:
- shorter download times for large pages
Cons:
- it actually needs a fairly new version of php
- it has to wait until all page contents is available (which can slow the browsing in some cases)
- it increases the server load (the compression can be tailored to adapt to the server's load but there's an increase nevertheless)
Anyway, this would be a nice feature to have but it can wait since there are some more important ones that need to be fixed/added first.
There are some articles about compression and samples
here (google cache - for some reason I can't reach the site now),
here,
here and
here (this one has a page allowing to test/show compression on user submited urls).