I'm not sure if there is an ETA. Here's what I'm going by:
"Once all the bugs in the flow are worked out, we’ll also incorporate it into the redsn0w GUI (but still leave the CLI freely available too). In order to maximize the chances of the jailbreak working for everyone, the redsn0w GUI will use native Apple iTunes libraries — this technique is slightly different than how the Chronic Dev GUI handles communications, and should provide nice combined coverage for all the odd computer configurations out there." - Dev Team Blog