05/11 - I've seen next week's season finale and the Rory-Lorelai stuff is absolutely heartbreaking. The episode also features a breakup and a reunion — neither of which involves Luke-Lorelai or Logan-Rory. Or any of the show's couples, for that matter. One [of the bombshells] involves Rory and the other Lorelai-Luke. And they're both doozies. One of them comes in the final five seconds and is spit-Snapple-out-of-your-mouth big. According to Amy Sherman-Palladino, Christopher simply didn't fit into the story [which is why he won't be in the finale]. But he'll be back next season.
spoilerfix.com

so i'd say it's safe to say there will be another season