The 60 day Challenge was open to all. There is no currently open 60 day Challenge.
There is a current contest at Hubpages for the month of September and there is always a 30 Day challenge and a weekly hubmob to participate in.
Have fun with the existing hub projects and keep an eye out for the next 60 day challenge in 2011.
..and the link above is not very relevant - try this instead: http://hubpages.com/business/How-to-make-a-passive... - Keep in mind , there is NO current 60 day challenge - but the hub above gives you all the info you would need to challenge yourself.