Comment Don't Print Them All (Score 1) 350
All that said, I would recommend only printing what you really want now (for frames, photo books, to put on the fridge, etc). Don't print them "to have a copy in 20 years". I do agree having a photo sharing site as the sole copy is a bad idea, but keeping them digital isn't.
I have all of our kid's photos on a computer at home (RAID 1 setup, but that may be too much for some to deal with), a second copy on a usb hard drive at home (for local backup), a third copy on a server I have in collocation (a similar solution would be mozy, carbonite, backblaze, etc.), and then the majority uploaded to Google Picasa for friends and family to view and order prints.
Sure, JPEG (what 99% of my photos are in) may not be around forever, but odds are, it isn't going to disappear overnight and I would much rather, in 10-20 year or whatever when JPEG goes away run some converting program overnight than deal with storing a bunch of shoeboxes of old photos.
Just keep your photos digital and put them on as many hard drives and in as many places as you can.