Main things to remember are :
- For desktop modern navigators ( Chrome 10/9, Firefox 4, IE9 =geeks&chuck norris at this time ) a canvas per object is better.
- But for now, this represents a little part of the mondial internet browsers park, so while waiting for a general up to date versions operation, user DIV tags with background images is better than canvas use.
- My personal tweak is to use the jquery-transform plugin, which has really results on oldIE for rotate and scales css3 replacement.
- And finally for me, last advice was to use individuals sprites rather than one for all objects ( sprites images must be small to have better performances in cut )
So here now, the complete facebook blog post can be read here : http://developers.facebook.com/blog/post/460