Take a couple of minutes to read these stories on TiVo, one at the New York Times and one at Slate.
They describe how TiVo has unleashed the attack dogs on its trademark -- and is asking that "TiVo" not be used as a verb or even a noun. It should only be used as "a proper adjective," as in TiVo DVRs.
Of course, the company can suggest what it likes. But cap it, and you'll be fine -- whether you're quoting people who TiVoed their favorite show last night, who want to buy TiVo-like products, or who just use TiVos instead of TiVo DVRs.
And you should never use the registered trademark symbol.
Interesting, though, is that some of this comes directly from the rules of the International Trademark Association.
NEVER use a trademark as a noun. Always use a trademark as an adjective modifying a noun. ...As Slate points out, "So much for classic ad slogans like 'Coke is it' or 'Leggo my Eggo!'"
NEVER modify a trademark from its possessive form, or make a trademark possessive. Always use it the form it has been registered in.
And, as usual, there's a conversation about the rules going on at Testy Copy Editors. It produced this classic response from Phil Blanchard: "Of course, I will use 'TiVo' as a noun or a verb whenever I please and TiVo can't do anything about it."