The power of “I [heart] X” is now such that the transitive verb “to heart” (spelled out, or written as “♥”) has become part of the Oxford English Dictionary. I’m not a lexicographer, but that seems like a quick turnaround.
Hat-tip to Ben Zimmer for bringing this to my attention.
♥ to heart
The new sense added to heart v. in this update may be the first English usage to develop via the medium of T-shirts and bumper-stickers. It originated as a humorous reference to logos featuring a picture of a heart as a symbol for the verb love, like that of the famous ‘I ♥ NY’ tourism campaign. Our earliest quote for this use, from 1984, uses the verb in ‘I heart my dog’s head’, a jokey play on bumper stickers featuring a heart and a picture of the face of a particular breed of dog (expressing a person’s enthusiasm for, say, shih-tzus) which itself became a popular bumper sticker. From these beginnings, heart v. has gone on to live an existence in more traditional genres of literature as a colloquial synonym for ‘to love’.
The entry:
heart, v.trans. colloq. (orig. U.S.). To love; to be fond of.Originally with reference to logos using the symbol of a heart to denote the verb ‘love’: see quot. 1983.
[1983 Associated Press (Nexis) 16 Nov., From Berlin to the Urals, teen-agers wear T-shirts reading, ‘Elvis’, ‘Always Stoned’, and ‘I (heart) New York’.]
1984 About Helmet Visor Screws in net.cycle (Usenet newsgroup) 26 June, Joe ‘I heart my dogs [sic] head’ Weinstein.
1986 Daily Collegian (Pennsylvania State Univ.) 14 Feb. 2/3, I just want to say to my Bunny Boo I Heart you Kathleen.
1998 Houston Chron. 10 May (Chronilog section) 7/1, I think he’s so cute. I heart him to bits.
2003 Time Out N.Y. 7 Aug. 77/1 If you heart dance like DJ Scott does, then hie thee down to this little drink spot tonight.
2009 A. Ham et al. Middle East (Lonely Planet) (ed. 6) 141/1 We heart the brownies (E£4).
2010 Observer 18 July 13/4, I hearted Take That‥with a teary passion that was deemed unbecoming in a Jesus and Mary Chain fan.
The Snowclones Database 
Are we sure that’s verbal? I would have called it graphical.
“♥” itself is graphical. But the addition to the OED is for the word “heart” used as a verb, in a new sense: The new sense added to heart v. in this update may be the first English usage to develop via the medium of T-shirts and bumper-stickers.