The new .Mac Web Galleries are great, but they unfortunately can only be built by iPhoto '08 and integrated into iWeb pages. Thanks to this RapidWeaver forum post from Günter, however, RW users have a trick for embedding those slick scrolling .Mac Web Gallery thumbnails into their pages. The trick more or less involves creating at least one or more .Mac Web Galleries, opening iWeb and using its new widgets feature to embed one of your galleries in an iWeb page, publishing to a folder and copying the specific piece of .Mac Web Gallery code out of that iWeb page and into a RapidWeaver Blocks page.
It isn't exactly pretty, but I think I know of a way to simplify this process, at least for some of you. The way I figure it, if you're already publishing an iWeb page to your .Mac account with your galleries embedded in them, you can just open your iDisk and drill down to Web/Sites, find the page you published with that gallery code and simply grab it from there. No publishing to a folder and creating more junk to manage and delete, since you're already publishing those pages and code somewhere.
As far as looking at the code on those pages, you can of course simply open them in a browser and use the View Source command, or you can find a text editor like TUAW favorite TextMate or even the free Taco HTML. For more questions on this you can try in the comments here since I know a good number of TUAW readers are also RapidWeaver lovers, but the original RapidWeaver support thread where I found this tip might be a better place if you want to get more thorough answers faster.