Emoji characters not displaying correctly on Windows 7

Microsoft has finally added Emoji (2, at least) to the Segoe UI symbol font in an update to Windows 7.

Microsoft KB2729094 titled “An update for the Segoe UI symbol font in Windows 7 and in Windows Server 2008 R2 is available” is presumed to be made available through Windows Update soon.

This article introduces an update to the Segoe UI symbol font in Windows 7
and in Windows Server 2008 R2. This update adds support for emoji characters
and some control glyphs that are included in Windows 8 and in Windows Server
2012.

Note Emoji characters come from emoji-capable platforms and devices. The 
platforms or devices enable users to easily insert emoji characters into
documents, email messages, or chat conversations by using an emoji picker
feature or an emoji palette feature. In Windows 8 or in Windows Server 2012,
these characters are inserted by using the on-screen keyboard.

Microsoft backports Windows 8 emoji for Segoe UI Symbol to Windows 7

You need a font that supports the new characters. I guess there will be an update to Windows 7 that included such a font. Alternatively you can install a font that includes the characters, for instance "Symbola" by George Douros: http://users.teilar.gr/~g1951d/. You can then finally see the cat "" and the monkey face ""! (In Firefox, you may need to set gfx.font_rendering.fallback.always_use_cmaps to true in about:config.)

I think many new emoji were added in Unicode 6, which came out a month ago. So probably there is not much use of the standard code points at the moment, nor fonts that support them.

The existing situation, I think, has different carriers using different code points in the Unicode Private Use Area or using Shift-JIS as per Wikipedia, so unless you had a font that matched what the phone had, you would not be able to display the characters.