With Mac OS X 10.7.2 there is a issue with the alert sound when the lid get’s closed.
It seams that Apple is muting the sound instantly when the lid is closed and there is currently no workaround to solve this problem.
Other Applications which offer similar functionality are affected too.
According to a Twitter statement from the developer of Lidpop Apple is aware of the problem and is going to fix it.
Growl notifications Plug Spy send when the lid get’s closed are not affected from this problem.