Currently the Nickelodeon animated series "Spongebob Squarepants" is in its 8th season of broadcast. The show was renewed for a ninth season January 3, 2011. The end of season nine will place the show at over 200 episodes, a track record that points towards the continuation of our deep sea friend's adventures.
No, Spongebob Squarepants is not being cancelled. In fact, Nickelodeon have confirmed that the cartoon will be around for a ninth series, as of January 2011. The following source confirms that Spongebob Squarepants is the longest running cartoon from the 90's. http://en.wikipedia.org/wiki/SpongeBob_SquarePants
SpongeBob in produced by Bad Clams Productions and the show was renewed for a ninth season on January 3, 2011. That is the current info. As of right now it is on the air and based on sales figures it will probably stay for at least one more.