The rule has not changed. The wording was changed to clarify the rule, as people were misinterpreting them. Of course it's easy to also misinterpret the new wording...
In the old wording, "within the prescribed time" means within the time you are
current. In my example above, it's from December 2014 to June 2015.
After "the prescribed time" (after you are no longer current), you have 6 months to work with a safety pilot. In the above example, from July 2015 to December 2015. This is the "grace period".
Otherwise, if you are no longer current for
more than 6 months, you have to take an IPC.
Here's the FAA guidance on the new wording (the "grace period" in bold):
In this technical amendment, the FAA
is revising the language in paragraph (d)
to clarify the intent of the rule. The
revised language makes it clear that a
pilot who has failed to maintain
instrument currency for more than six
calendar months may not serve as pilot
in command under IFR or in weather
conditions less than the minimums
prescribed for VFR until completing an
instrument proficiency check. A pilot
whose instrument currency has been
lapsed for less than six months may
continue to reestablish instrument
currency by performing the tasks and
maneuvers required in paragraph (c).
http://www.gpo.gov/fdsys/pkg/FR-2011...2011-32333.pdf