Effectively, nothing changes about the current situation. Right now, no royalties are collected for internet video that is free to end users, and this promise was extended to December 31, 2015, earlier this year. All they've done now is extend this promise perpetually, without saying why.
The why is pretty clear to anyone who's been following this debate, of course. It's no secret that with YouTube, Google pretty much mandates the default codec for web video. Now that Google has launched the WebM project with wide industry support, the sword of Damocles is dangling above YouTube's H264-centric approach to web video. Adobe's promise to include WebM support in Flash, as well as Microsoft's change in policy to also allow WebM support in IE9's HTML5 video implementation surely turned up the heat for the MPEG-LA.
Effectively though, nothing has changed. H264 is still a legal minefield that nobody really seems to understand, and you're no safer from these
mythical possible submarine patents when implementing H264 than when implementing WebM. While Theora did not have a large industrial backing, WebM does, meaning the MPEG-LA can no longer rely on the FUD-tactics of yore.
New promise or no, any form of commercial use still requires paying money to the MPEG-LA; even having an advertisement on your website which also happens to host an H264 video can be dangerous. Since the MPEG-LA has already stated in no uncertain terms that they're willing to go after individual end-users, H264 is simply not a wise choice.
Luckily, WebM already has better browser support as it is, so it's only a matter of time before the MPEG-LA's license to print money starts to smear a bit. Mozilla and Opera have already made it very clear they're not going to pay the MPEG-LA, so these two will only support WebM and Theora. Google's Chrome does support H264 (Google is rich enough), but obviously, Chrome does WebM and Theora as well.
While Internet Explorer 9 was supposed to use H264 exclusively for HTML5 video, Microsoft later changed this policy to also allow WebM when the user has this codec installed. Nothing has come out of Apple just yet, but Apple has been a very active proponent of H264 from day one, and it's unlikely their mobile devices will ever support WebM. Safari on the Mac will eventually support WebM through a QuickTime plugin, but I'm sure Google is waiting for QuickTime X to mature and actually get a plugin framework before committing to that one.