Cleantech bubble?

Cleantech is here to stay investors claim and vc-money is still flooding into the sector. Here are some recent examples of companies that attracted the investors:

Silicon
http://www.redherring.com/Article.aspx?a=22834&hed=Startup+Gets+%246M+to+Do+the+Dirty

Biofuels
http://www.redherring.com/Article.aspx?a=22765&hed=VC+Puts+Double+Bet+on+Biofuels

Solar
http://www.redherring.com/Article.aspx?a=22705&hed=Funding+Dawns+for+Solar+Firm

http://www.redherring.com/Article.aspx?a=22649&hed=Advent+Solar+Secures+%2470M

Big companies are also interested
http://www.redherring.com/Article.aspx?a=22411&hed=GE+to+Double+Cleantech+Investments