Deprecation Warnings in API

When I see deprecation warnings in the API....

## DEPRECATION WARNING: This method will become a separate plugin
when Rails 2.0 ships. ##

... how should this affect how I use the method? Should I not use the
method? Or does it just mean that when Rails 2.0 ships and I update
I'll have a lot of re-work to do?

It seems that there are a few helper methods for AJAX, JS , etc. that
will go away.

What is the basic timeline / schedule for Rails? Is 2.0 the next
planned major release? When (loosely) is 2.0 planned for release?

Thanks,

Blaine