If you have migrated from Blogger classic to Beta these are good news for you. The recent comments feeds are working now and you can easly add a recent comments section in your blog's sidebar.

Sign on to blogger, click on layout, click on page element and select add feed option and then write the following as the feed url:

http://yourblogname.blogspot.com/feeds/comments/full.

you can select wether to display the author/date of the comments.