Although the spam wasn’t on my site for more than a few hours, someone has pointed out to me that my Google PageRank for the homepage has dropped from a reasonable and healthy
PR 6 to ZERO. While PageRank is a very weird thing and it could be any number of things including a random inaccurate report from Google, it seems more likely this is a penalization from them for the spam. Many of my subpages, which get crawled far less frequently, still have their PageRank. It’s not just the PageRank, many searches that would have brought up the homepage (e.g. my own name) are now far down the SERP pages when they used to be #1. This of course will be seriously affecting my traffic until my PageRank is restored, if it ever is.