So I designed this great mockup with round cornered images, and then realised it depended on being able to see a background image through the corners, and not just a flat colour. No problem - CSS3 border radius to the rescue!
But this wasn’t going to work in IE<9 even with any of the myriad javascript/html hacks to get rounded corners working as they all depend on a flat background colour.
So I discovered setting my image thumbnails with phpthumbof it was really quite easy to get this effect. Pass in the rounded corner filter with horizontal and vertical radii, and also a file format of png and boom! Too good not to share.
<img src="[[phpthumbof? &input=`assets/images/products/[[+product.image1]]` &options=`w=120&h=77&fltr[]=ric|10|10&f=png`]]" width="120" height="77">
This produced a png with transparent rounded corners each 10px radius.