If you’ve decided you want to stick around Google+ for a while, or if you simply want to take advantage of the unlimited storage space in Picasa, you’ll likely want to transfer over your photos from Facebook.
Fortunately, it’s quite easy! Head over to picknzip.com and it’ll help you export them all out. Once you’ve downloaded all of them, just head over to Google Plus and start posting!
BuzzingUp.com has a full write-up about this technique, including some very helpful photos.