Yes indeed. They usually give the next format during the first week (or so) of June. My three most likely guesses for the 2009-2010 format (not in any particular order):
1) The next format will be GE-on.
Potential reasons:
*The BK promotion will be giving out Palkia and Dialga cards from that set, and although they are also Blackstars, who knows what promos will be rotated?
The BK cards are coming out in June. BK doesn't care if the cards they released in June will be illegal to play in tournaments in September because most people who collect Pokemon don't play competitively in tournaments.
*If Unown G is not in the format, Machamp will be a major problem given that the next few sets are probably going to be SP sets, unless there's going to be some card that reduces the impact of Take Out.
We have never had a rotation because certain cards would be more powerful than others.
*Felicity's Drawing was printed in the Drill Point deck, which has not been reprinted since GE, unless it's coming in POP 10, a promo, or the next set.
Higher chance of it being reprinted in POP10.
2) The next format will be DP-on (no rotation).
Potential reasons:
*The reasons above, plus...
*Some of the Pokemon-Lv. X (i.e. Porygon-Z, Rhyperior) would not have legal uses. Granted, that was not something that kept Rocket's Persian EX during the last year of the EX series in Modified, but this is different since these cards are actually "in" the set.
There will be a new Rhyperior released in the next set that comes out around Worlds. Also, the Porygon Z promo will be legal next season, allowing for people to use the Porygon Z lv.X.
3) The next format will be MD-on.
Potential reasons:
*They may want to rotate 4 and then 3, since my guess is that the 2010-2011 season will be PL-on. But, there's no reason they couldn't do 3-then-4.
TPCi prints 4 sets a year, and it makes sense for them to rotate out 4 sets a year.