Syllabify English words - kind of
Lua, 292

Lua might not have been the best language to do this in, but it works. It pretty much flows like the question asked. The rules are mainly in order with some optimizations: #2 is skipped (it isn't needed unless there is a one vowel word with "ck" at the beginning), and the ck and y rules are gone through before the rest of #4 and #6, which are combined. Since some vowels in the word need to be captured twice (after one hyphen and before another), that search is performed twice.

i=io.read()v="([aeiou])"for s in i:gfind("%l+ ?")do
if s:len()~=4 then
s=s:gsub(v..v,function(x,y)if x==y then return x..y;end;return x.."-"..y;end)s=s:gsub("ck"..v,"ck-%1")s=s:gsub(v.."y"..v,"%1y-%2")for b=1,2 do
s=s:gsub(v.."([^aeiou\-]?)([^aeiou\-]+)"..v,"%1%2-%3%4")end
end
io.write(s)end


Ungolfed

function checkEquals(x,y)
    if x==y then 
        return x..y
    end
    return x.."-"..y
end
i=io.read()
v="([aeiou])"
for s in i:gfind("%l+ ?") do
    if s:len()~=4 then
        s=s:gsub(v..v,checkEquals)
        s=s:gsub("ck"..v,"ck-%1")
        s=s:gsub(v.."y"..v,"%1y-%2")
        for b=1,2 do
            s=s:gsub(v.."([^aeiou\-]?)([^aeiou\-]+)"..v,"%1%2-%3%4")
        end
    end
    io.write(s)
end


Test it here: http://ideone.com/g57TzA