I found the best place to get information would be the
Wikipedia article.
Also, Spore and some other popular games have it, and people wanted to boycott spore because of this. But it was Spore, so it kinda didn't happen. The newer versions of SecuROM seem to be safe, though, they just add an extra process that automatically starts with your computer (only really noticeable thing), that can't be easily removed (I've uninstalled Spore, it's still there). It causes no trouble, though.