Lately they've been taking longer and longer to do updates. I believe it was around Christmas time when there was hardly any updates. IIRC, they went through Halloween and Christmas without much of anything.
I heard an unsubstantiated rumor that HSR was in negotiations with Cartoon Network to Produce a regular show on Adult swim. If true this could be some of the reason the site hasn't been updated.
It probably has more to do with the fact that the father of the two brothers who run the site passed away in early April. They had enough updates underway to continue through May, and I guess are taking a break.
I know the site was their sole source of income, so I imagine it will be back unless they decide to just move on. Supposedly the dad was "the heart and soul of Homestarrunner.com" they said.