Dor dt lsr ydnarkl wdoljbflcdok ld er krro bl b KsmddWdo: b hbk fdqrjra [yrbt eydqrj].
No instructions given for this one, but it clearly looks like an encoded message. Assuming that there's a one-to-one mapping between letters, it's a pretty safe assumption that the letter 'b' represents either an 'a' or an 'i.' Maybe it's a simple shift cipher. Let's try that.
Cnq cs krq xcmzqjk vcnkiaekbcnj kc dq jqqn ak a JrlccVcn: a gaj ecpqiqz [xqas dxcpqi].
Kvy ka szy fkuhyrs dkvsqimsjkvr sk ly ryyv is i RztkkDkv: i oir mkxyqyh [fyia lfkxyq].
Those are both gibberish, so it must not be a simple shift cipher. Well, maybe it's just a one-to-one mapping like the cryptograms I've seen in the newspaper. There are still other ways to analyze the puzzle. We could run a frequency analysis to determine which single letter most likely represents the letter 'e,' and so forth. We can look at letters that occur in pairs often. We can look at letters that appear in consecutive multiples. And we can look at capitalization. As it turns out, the phrase KsmddWdo represents ShmooCon. Using that as a base, it doesn't take too long to eliminate letters and hack at the puzzle until you find the answer.
One of the loudest contraptions to be seen at a Shmoocon: a gas powered [leaf blower].