I have been able to successfully patch the ads out of AIM for OSX, including removing the blank space. However, I still need to look into how to make this an automatic patcher (in OS9 you could just use ResCompare).
Also, I am not going to release this until AIM for OSX goes final. Otherwise I'm afraid AOL will find out and will just change the location of things and make me go back to square one and start over, which I really don't have time for.
So in the meantime, be patient, or use Fire.app... since AIM for X doesn't support any extra features yet anyhow.