There are even instances where manufacturers closed assembly or blade facilities when the PTC died out.  I believe Micon suffered as well as Vestas, which led to Micon's downfall and resultant purchase by Vestas.  The boom and bust cycles affect affect the entire supply chain, for example when tower manufacturers open and close.  The end result is the absence of economies of scale and long-term infrastructure investment planning.

The PTC currently expires at the end of 2008, and significant Capex has already been made.  Most analysts had no worries of an extension until recently.  There was talk of decoupling renewables from the contentious energy bill, where the dinosaurs are fighting it out.  Several days ago Pelosi announced that there was some kind of agreement bringing renewables back into the mix, but that remains to be seen.  Since there is general bipoartisan support for the PTC it's hard to imagine it wouldn't be extended, but i've seen weirder things happen around energy policy in amurka.

AWEA was going for a 5 year extension, and i believe at least 3 years can be counted on.  But the risk of no extension has surfaced over the past two months.

"Life shrinks or expands in proportion to one's courage." - Anaïs Nin