You're in luck. Planetary #24 is out January. #25 February/March. #26 March/April, with the final ever issue, #27, sometime later in the year, probably summer.
PLANETARY #24
For months Elijah Snow has been pulling back from his fellow Planetary agents, following a personal road map to his own mysterious agenda. Now the curtain will begin to be drawn back and the some of the deepest secrets will at last be revealed... like patterns in a snowflake. And if the last pages of this story don't leave you gasping for breath and begging for more, nothing will!
From Ellis' Bad Signal, in Spring 2005:
I'm nine or ten pages into the new script (24), and right away I've wrapped up the connections between the Hong Kong cop, the Melanctha issue and John Leather, hopefully clearly explicated what the Century Babies do, explained why the Four let Planetary live, given a fairly strong hint about what The Drummer is, and described the above and below of the protective systems existing around life on Earth in the Planetary "universe".
Release is scheduled for January 18th, 2006.
Ish 25PLANETARY #25
From Ellis' Bad Signal, October 31 2005:
#25, by the way, covers a lot of what John Stone's been up to.
The ofiicial blurb: "The final act begins! Elijah Snow draws together elements from nearly everything he's investigated since rejoining the team, to lay a trap for the two remaining members of the Four. But the Four had fully fifty years to prepare their defenses. Fifty years since their rocket entered the space between universes, and they were changed... but how?" On sale February 22nd.
PLANETARY #26
From Ellis' Bad Signal, October 31 2005:
Now halfway through script for penultimate issue of PLANETARY, which is #26. I laid the plans for the last half of this issue back during the first year of the book. It almost seems too simple, now, as I connect up the dots. Hopefully it'll be satisfying. Not every mystery associated with the book will be tied up; life's like that, and some of the ideas are more interesting as mysteries than as solutions.
Release is roughly scheduled for late March, 2006.
PLANETARY #27
From a couple of Ellis's Bad Signals, spring of 2005:
Cassaday and I are talking about a little stunt for the last few issues of PLANETARY -- I'm pretty sure right now that 27 will be the last issue.
By the end of July, PLANETARY will be pretty much done, save for the aftermath/closing issue, which I may have taken off the schedule and released a few months after #26 as a coda.
Some of the powers-that-be over at WildStorm have been talking about the tentative plans for the remaining issues of Planetary. Separately, Wildstorm VP and General Manager Hank Kanalz and editor Ben Abernathy have mentioned an epilogue-type issue later in the year, as Ellis' and Cassaday's schedules allow. So the final issue should appear some time in 2006.