Wow, must be this year's new model, includes a manic rodent as bonus....
Ok, all laughs and giggles aside, it is called the trackpad. Mice dangle outside desktops. This article may help tame the wild Mickey: http://support.apple.com/kb/TS1449
If your MBP is still covered under warranty, contact AppleCare. If not, you can still make a free appointment with the "genius" bar.
Here is a thread which may point to what is wrong: https://discussions.apple.com/thread/1365569?start=0&tstart=0 (the trackpad ribbon cable).
One thing you can try is a PRAM Reset: http://docs.info.apple.com/article.html?artnum=2238
-Shut down your Mac.
-Turn on your Mac and immediately hold down the command-option-p-r keys.
-Continue holding down these four keys without letting up on them until you hear the startup sound for the second time, then release them and let the Mac boot normally.
My eratic cursor seems to be fine after doing the tilt to side trick posted at https://discussions.apple.com/thread/2522743?start=0&tstart=0. Apple Genius has ordered a new trackpad but all is good here for now.?