This was revealed by Pod2g in his recent tweet that we have made good progress on the jailbreak for A5 devices i.e. iOS 5.1.0, if lucky we could expect it in a week.
Note: You will need to update your iPhone 4S and iPad2 to 5.0.1 for new jailbreak therefore do it by the time of release of new jailbreak iPhone4S and iPad2.
Following is the snapshot of his tweet.
“I made a step today for the A5. With some luck we could expect a release in a week.”