WordPress has lost the domain that Akismet was hosted on — and SVN users are stuck. Since the domain is no longer valid, when your SVN client attempts to query it for the Akismet plugin (which is included via something know as “svn externals“), it gets a HTTP 501 error, and the entire SVN update fails. For some, that might be OK, if all you have on SVN is WordPress, your plugins just don’t get upgraded. No biggie.
Some of us however depend on SVN for a lot more than just WordPress. NeoSmart Technologies is such an example: we jumped on to this great CVS replacement the minute we heard about it — it’s that great. At NST, we have our Gallery, Blog, various small scripts, and most importantly, our download system on SVN. We don’t even use FTP anymore, just SVN the files from our side, SSH into the server, and update the repo. It’s that easy.