iPhoto 6.0.1 (correction: 6.0.2) has refined its ability to publish images in your library via RSS. And it works great — in some ways almost too well. You need to be aware of the resolution you’re sending out to control bandwidth requirements and how your images can be used.
When you enable an album for photocasting (highlight the album >Share > Photocast), you have the option of setting the image resolution you’re sending out: small, medium, large, and original size. I tested these settings with a pictures I captured with a Canon Digital Rebel XT DSLR (8.2 MP) and a Casio EX P505 digicam (5MP). The original resolution for the Canon was 3456×2304 and 2560×1920 for the Casio. When I chose the “small” option, the image iPhoto served was 639×426 (Casio 640×480). “Medium” sent out 1279×853 (Casio 1280×960), “large” syndicated 1920×1280 (Casio 1920×1440), and “original” was as expected, 3456×2304 and 2560×1920 respectively. The output differences between the Digital Rebel and the Casio are because the Rebel captures images that are more rectangular than typical compact cameras.
If the goal of your syndication is for online viewing only, I recommend that you keep the image resolution at “small.” Your recipients will need less bandwidth, and you don’t have to worry about folks making high quality prints from your work. If you do want to enable printing, however, the “medium” output setting enables folks to make a photo-quality 5×7 print, and “large” can produce a very nice 8×10 print. The “original” output is of course dependent on the resolution of your camera.
I think for friends and family sharing, the “medium” setting is all most folks would need. This is a nice compromise between reasonable bandwidth requirements (200-500kb per image) and decent printing resolution. If you want to speed things up however, the “small” output is a svelte 70-150kb per shot.