See the post here: http://blogs.msdn.com/b/windowsstore/archive/2012/09/11/windows-store-now-open-to-all-developers.aspx .
This includes individual accounts now so if you tried signing up before and got a message about it only covering company accounts, you can sign up now. Don’t forget to verify your account and setup your payment and tax information. Also, if you are an MSDN subscriber you should be able to get a code from the MSDN site that will give you a free year (saving $49 US) but you will still need to submit some form of payment (e.g. credit or debit card) for verification purposes and so that they can automatically rebill you at the end of the subscription year (unless you’ve cancelled your account for some reason, of course).
Go forth and register and make awesome games and apps for me to buy and play and use!