Hi.
I'd like to elaborate on my original comment. I didn't take any offense, Mort. Your point was completely valid.
iMac (note the lowercase 'i') is not copyright; it's trademarked. This is a different kettle of fish. Forget copyright. It isn't relevant to the discussion. Would a magazine called IMAG infringe this trademark? Most unlikely. Infringement would occur if IMAG was 'passing off' as an Apple or Apple-endorsed product. For instance, if the magazine was called iMAG (with the lower case 'i'), used the same font as the iMac logo and other graphic or editorial devices to make it appear as though it was something it wasn't (ie an Apple-certified resource), then its publisher would certainly get into trouble. But, given the difference in name, typography and - I admit to hazarding a guess here - an editorial remit that extends beyond the Apple platform, it would not be an issue.
How qualified is this opinion? I am not a lawyer. I have a couple of decades of experience in journalism and publishing. I have been educated in the matters of copyright and trademark law, to the extent that most journalists should be. Nevertheless, if in doubt, take professional advice.
One last thing: I am, of course, assuming that IMAG isn't already a trademark. Trademark searches don't cost a lot, by the way.