A good way to find the latest important events is to monitor the queries from a search engine and look at the queries that suddenly become popular. Google offers a list of "hot" queries updated hourly. For each query, you can see a chart that reflects its evolution and a list of search results that could explain why it became popular.
Now you can subscribe to Google Hot Trends' feed and keep an eye on what people are searching for. Note that the list is restricted to the US and the first feed item shows the most popular queries from the last hour.
The presentation isn't great, but this feed makes it easier to create web applications that use the data. There's also a third-party gadget that displays the top 10 queries.
You can use Google Reader to reconstruct the archive or just to search the feed and see how often the iPhone, Britney Spears or Ivan the Terrible were a hot topic.