Apple are not getting rid of iWeb, just MobileMe publishing.
iWeb is an app and you can still continue to use it. You just need to upload your site to another host such as GoDaddy or HostExcellence etc.
You are correct that Blog comments won't work - they were MMe only, but there are alternatives, such as adding http://www.intensedebate.com as a comment system instead.
You could always consider using WordPress as a blog instead and just linking to it from your website - this is what I have always done and I have managed to change the templates in WordPress, so they have the same colours and look of my website.
Have a look at http://www.weebly.com too.
You don't need to look for an alternative to iWeb yet. It's an app and will still work.
While iWeb is an app and will still work (assuming that it does with Lion), for many of us who have sites that are centered around many photopages with slideshows, it will not work--at least not like I want it to. Not unless either Apple updates iWeb so that this feature is not dependent on MobileMe servers, or I try to use the fix suggested by Old Toad and Roddy. I'm not feeling real comfortable with that fix at this time. I can't imagine that going forward I'd want to update my sites or create anything new with iWeb unless I know I'll be using iWeb for the forseeable future. Right now that's not the case. So, for people like me, we do need to explore alternatives to iWeb.
I think Apple needs to tell us what the plans for iWeb are going forward instead of acting like there will be no issues or problems down the road.
third party commenting system such as http://www.intensedebate.com/ can be fully integrated in iweb blog with no monkey business (resizing iframe), but you need to know how iweb widgets works:
@Steve Mouzon, @ Rob Westle,
slideshow's problem is just cosmetic, a problem none the less... easy fix btw.
the bigger problem is with mme blog comments, photos comments, your blog's comments will be gone when apple shuts down mme servers because the comments are on their servers.
RAGE Software (Canadian) site advertises migration from moble-me blog to WordPress with a plug-in: http://www.ragesw.com/products/iweb-to-wordpress.html
They also advertise iWeb optimized web-hosting. However, have no phone support and did not answer my e-mail about inquiry to migrate to their service.