Essentially, Kerry was asked what Syria could do to avert strikes, and he made a remark about complete chemical disarmament, before dismissing it as 'not going to happen'. A few hours later, the Russians made an offer to Assad to essentially do just this, with the remark that the Syrian government had 'welcomed' this offer. The US is officially holding a suspicious hard line, the UK is cautious but optimistic, not sure about elsewhere.
Like I said, perfect face-saving measure. Obama gets an out from his red line, Russia doesn't have to go headlong into major issues over an ally along with removing the possible future threat of chemical attacks, and Syria has a security council backer to guarantee fair treatment for disarmament. They of course have made no statement admitting that they have said weapons, but the fact that they 'welcomed' the offer means that either they do, or they're clawing for time - which is risky, given the implications of going along with the offer even in principle.