Reports at this point are very, very sketchy. But it seems as if iPhone hacker @comex and the dev team have revived the older jailbreak site, http://www.jailbreakme.com according to recent twitter chatter.
The site is of course getting hammered at this point so it’s too early to confirm anything substantial, but we’ll be doing some refreshing and let you know after the break.
Update: confirmed to work on a user with a 3GS. Here is an alternative link to try if the one above isn’t working for you.
Update 2: welcome back cydia on my iPhone 4! I personally had better luck over 3G with the first link!
Update 3: So I jumped the gun and failed to mention (thank you Inception) that I have lost both MMS and Facetime capability from my iPhone 4 for the time being. And it looks as if the dev team is well aware and working on the issue. I would recommend holding off on jailbreaking if you rely heavily on either of these features.
Update 4: It seems now that if you were experiencing issues with MMS and FaceTime that doing a restore and re jailbreaking will fix the issue. This has proven to be the case on my iPhone 4 and remember to turn facetime back on!