[edmoffo]

Not just hieroglyphs... Unicode includes anything you can imagine

[bluerobotcat]

It includes many things, but not, for example, an 'i' dotted with a heart. And to represent mathematics well you need to use MathML.

[Someone]

There was a request for it: http://www.evertype.com/standards/iso10646/pdf/n258a-heartdo... (but do note the date)