It’s now an entry in OED, I hear. Anybody know what the actual OED entry says?
The OED doesn’t actually have an entry for ‘♥’, or ‘<3’. It has a new definition for ‘heart’:
trans. colloq. (orig. U.S.). To love; to be fond of.
As to how to pronounce ‘<3’, I think it would generally be the same as heart. To orally spell it out I would say “less than, three”