Picasa Web Albums beta has been released by Google. You can upload your photos online to a generous 250 MB and keep them privately, only accessible by your Google account. There is also an option to place some of your photos in a public gallery.
For Picasa users, there is a new version with a web albums feature integrated that allows you to select multiple pictures and upload them to an album. Otherwise, you can just upload them by browsing for up to 5 pictures and uploading them. For an additional $25 a year the storage limit can be increased to 6GB, giving you peace of mind on where you are backing up your photos.