A Google Maps Help thread has reports of some map developers having issues embedding the street view versions of Google Maps on their web site.
The issue was first reported 9 days ago by a guy who runs StreetViewing.com. The old embeds are no longer working for him, so now he has to go in and replace all of those with the new code. That can take a lot of time.
Brian from the Google Maps team actually confirmed the issue on Friday and said he notified the team. Brain B from Google said:
Just wanted to hop in here and assure everyone that the team is looking into this issue. When I have information to share, I'll post it here.
Thanks for all of the detailed reports.
Forum discussion at Google Maps Help.