Unfortunately, AFAIK, emoji emoticons that are built into iOS 5 are not cross-platform compatible. Only other Apple products (maybe just iOS devices?) can read them if you send emojis to them. Sorry.
However, if you have a jailbroken phone with
biteSMS (from Cydia, $9.99, USD) installed on it, you can set it up so that you see emoticons as emoji characters even when they are sent as ASCII characters from other manufacturers. If doesn't help your recipient see the emojis - but
you can.
Also, if you use the biteSMS emoji selection, you can also pick emojis to include in your text - biteSMS will convert them to ASCII for your non-Apple-device-owning recipient. IOW - you only have see and use emojis.
I just tested this by having a text conversation with my Google Voice account. I see the emojis on the phone, even if sent as ASCII from Google - but my Google Voice account only sees ASCII. Oh, and when I went into my regular Message app on the phone, it didn't see the Google Voice ASCII characters as emojis ... they were just text. So, it's biteSMS or nothing (that I know of).
That's the only thing I got right now - be jailbroken and have biteSMS. Sorry.
Marilyn
P.S. And no, I'm not shilling for biteSMS - it's just that I find it is a very cool jail breaker's tweak!
P.P.S. Thanks for asking this question, BTW. Cause, now I know what to do when I text with people who don't have iPhones - but I want to see emoticons. Made me do the research and so I learned something. Kewl!