After the news broke earlier in the year that the stage show Mamma Mia! was being made into a movie, filming took place over the summer of 2007 at:

1. Pinewood Studios, England (10 weeks starting June 2007) 
2. Damouhari, Skiathos and Skopelos (Greek Islands) (5 weeks September to October 2007)

Both Benny and Björn filmed short cameo parts:

1. Benny appeared first in the film during the Dancing Queen sequence: he appeared as a Greek fisherman playing a piano on a pontoon. Before its release, it had been rumoured that Benny had taken part because a picture emerged from the film set in his fisherman's outfit. 
2. Björn's appearance came right at the end of the film during the end of Waterloo where he could be seen dressed as  Greek God holding a lute!  On one of the DVD releases, one of the bonus features was the full Björn cameo - pictures included above.

The rest of the cast were already well known: Meryl Streep, Colin Firth, Pierce Brosnan, Julie Walters, Dominic Cooper, Christine Baranski, Amanda Seyfried and Stellan Starsgård.

Benny wrote all the incidental music for the film (ie. all the subtle background bits you don't really notice normally!). This included a very subtle Knowing Me, Knowing You during the scenes where Sophie sneakily takes Bill, Sam and Harry to the old goat-house after their arrival. This was a way of including the song which wasn't included as a song in the film. Knowing Me, Knowing You was also played on a by the Greek trio playing trumpt/tuba/clarinet as Sophie walked down the aisle.

The world première took place at the Odeon Leicester Square in London, UK on Monday 30 June 2008 attended by Benny, Björn and Frida.  The film was released in London on Friday 4 July 2008 and across the country from Friday 11 July 2008.

The Swedish première took place at the Hotel Rival, Stockholm, Sweden on Thursday 3 July 2008 attending by all four ABBA members.

In May 2017, it was announced that a sequel, Mamma Mia! Here We Go Again would begin filming that summer for release the following year.

UNFINISHED

Broadcast information:
Friday 21 July 2008
Wednesday 23 December 2015, 20:00-22:00, ITV3, UK
Thursday 24 December 2015, 17:50-20:00, ITV3, UK

Release information:

Mamma Mia! - The Movie (Benny & Björn), 2007;
Mamma Mia! Here We Go Again (????), 2017

Thanks to Richard Knight. Graham Piper, Mark Hannam, Mary McConnaghy, Ryan Cameron, Pascale Ranson, Erik Menkens, Grant Whittingham and Pieter Wever c/o ABBAMAIL (no longer online) and ABBA Annual, Ian Cole, Jozsef, Erik Liebstaedter and Claire Richland.
YouTube linnks c/o deboraw and Daniella Martins