Sort me out re punctuation after emoticons please

[Hassled]

Does an emoticon replace punctuation? I recently posted: "I'm open-mouthed in admiration ." Was the full-stop necessary? Should I just get out more?

[maidamess]

No full stop required

[JaneHH]

I worry about this too, Hassled .

My little rule is (pedant hat firmly on head):

• full-stop after emoticon when a sentence precedes the emoticon
• no full-stop when the emoticon is just randomly attached to a paragraph (most often in a whole row of emoticons like this )
• brackets are another matter entirely

[JackieNo]

I don't really have a rule as such, but I generally do use punctuation after them - can't stop myself.

[Hassled]

So I have a yes, a no and an "it depends" (.) Thanks!

[asicsgirl]

but do you need a space before an emoticon?

[Madlentileater]

have consulted DDs....they say no, not on the internet.
what I want to know is, why don't I feel obliged to start new lines with a capital letter, when they are clearly, structurally speaking, sentences. DD2 says that on MSN they don't use punctuation at all
or, to clarify you don't need to, because it's like a conversation, so...you only use the punctuation that you would use in speech, which apparantly is commas and exclamation marks and question marks. So just poor old full stops that get the cold shoulder then.
Fascinating.