Some interesting comments from (interim) government digital chief Chris Chant, speaking at the SOCITM spring conference this morning:

(Alphagov) is not perfect and it could be significantly different when we go live with the real deal, which will probably be in about a year... We want to make clear the infrastructure we put in place is available for local authorities to use.
Guardian Government Computing

We will work out what the appropriate branding is in due course... We won't ask for any money from departments and we'll still save money... (Local authorities would be invited to use the infrastructure) probably at no cost or marginal cost... (The permanent head of digital will be appointed) in the next couple of weeks.
ukauthority.com

I'm only going by the quotes in those articles - but that seems like much more than 'let's see how the alpha is received'. But for those who were asking if it would be a replacement for Directgov - no answer yet, but definitely maybe.