It turns out that Microsoft published Service Pack 1 for the .NET Framework 1.1. I don't see it publicly announced on the MSDN homepage. So either the page has been made available too soon (and will be pulled again) or Microsoft doesn't think this Service Pack is a big deal...
Anyway, it's 10MB big and covers quite a few issues, which I will not mention here. Check them out yourself.
I am curious who wrote the Dutch description for this service pack. It's obvious this was not a techical person. Check this: 'Daarnaast bevat het service pack een samenvatting van alle gerapporteerde problemen van klanten die ...'. Meaning: the service pack contains a summary of reported problems. Oh, that's nice. I get a list of issues that other people have had with the .NET Framework. I prefer fixes to these problems.
And this one: '...voor het voorkomen dat gegevens worden uitgevoerd'. This says that it prevents data from being run. I've never seen that before. Applications run, code may get executed, but can data be run?