Well, I'm no expert, but my assumption is that they had to talk to Linotype (whom I believe owns the rights to Helvetica Neue) to get permission to customize and modify the typeface. Most standard EULAs have a clause prohibiting modifying, renaming, etc., unless express permission is given, so they probably had to work out some deal (which I'm sure wasn't a big deal money-wise for a company like IBM).

Unfortunately, though, renaming/modifying type without permission is not as uncommon as you'd like to think, even for big companies. I've seen a few such cases here on Typophile if memory serves, with the most famous recent case being the one here and here.

I've seen a few fonts modified for educational publishers to include D'Nealian letterforms. The new characters in some were quite ghastly.

If the derivative font contains the trademarked name of the original, in this case Helvetica, you can be pretty confident that it's licensed, especially when someone like IBM is involved. Check the (c) and TM strings in the font for confirmation. Another similar examples would be Apple Myriad, used under license from Adobe. However in some cases lack of the original TM name may not mean it's a knock off - for example FF Transit is derived from Frutiger under license.

Thanks a billion auricfuzz and Ehague.

Oh, and of course sii.