Not at this time.
The SmugMug galleries can be used within pages, posts as image galleries. We did this to create a situation where you don't need to re-upload hundreds of images. As a SmugMug user, you have already created image galleries, uploaded, organized, etc... Why redo all that when creating your website's galleries?
But specific sections of the site like the Home Page sliding panels or the slideshows for the blog and hom pages, are limited to either one image or just a few and require specific sizes and proportions.
It would be more work in this case to make a user scan potentially hundreds of galleries and thousands of images in SmugMug to add them here.
There is also no way to know if they are the correct size for these areas.
To add SmugMug images into these areas, it is easiest to just download those images, make sure they are correctly sized and add them where needed.
There is also the chance that SmugMug galleries are renamed, reorganized, images removed etc. There would be no indication within SmugMug that any image was being used somewhere else. While a user will probably remember that an entire gallery was used on the site, noticing and remembering that a single image was used somewhere is probably unlikely. We would not want actions on SmugMug to effect something as prominent as the home page of your website.