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Microsoft's notorious Patch Tuesday has been replaced by Update Tuesday, at least for today, as the company makes sweeping alterations to Windows 8 and its core apps.

The update to Windows 8 Release to Manufacturing (read the review) aims to improve what was already solid performance in Windows 8. In the blog post announcing the update, Windows president Steve Sinofsky explained that the update would be seamlessly available for all Windows 8 machines when they boot up on October 26 and thereafter. "By developing better test automation and test coverage tools we are happy to say that Windows 8 will be totally up to date for all customers starting at General Availability," he wrote.

Basically, this is a strong indication that Microsoft has learned the valuable lesson of releasing unobtrusive but important updates when they're ready, instead of saving them for larger, less frequently issued "service packs". That's not to say that a Service Pack update couldn't be in the works for Windows 8 in the future, but this is definitely a shift in how Microsoft gets things done.

The changes are all under the hood improvements. We haven't yet had a chance to verify any of the claims, but Sinofsky wrote that power efficiency has been tweaked to extend battery life; audio and video playback has gotten better in "many scenarios"; application and driver compatibility has gotten better as well; and performance improvements have been made to the Start screen and the core Windows 8 apps.

Speaking of those Microsoft-built apps, nearly all of them saw updates today, and many of those changes were substantial. The big four productivity apps of Mail, Calendar, People, and Messaging got some much-needed improvements that I said in August would be required for Windows 8's success back in August.

Mail now has Conversation view for the Inbox, IMAP account support, and you can accept or decline calendar invitations directly from an e-mail. You can capture and update your account picture from People; search for a contact from the Messaging app, and search has been improved. These are substantial changes, especially Calendar integration with the Mail app, but in a half-day's use it's clear they don't go far enough. I would be surprised if there weren't more improvements soon as Microsoft pulls its apps into feature parity with the competition.

Another dozen apps also received updates. From the SkyDrive app, you can now search in-app, rename and move folder and files, and customize the sorting order. It also has a new first-run experience to smooth out the learning curve. This is important, and hopefully bodes well for getting a solid operating system tutorial when Windows 8 launches. Otherwise, those screen edges are probably going to confuse a lot of users.

The Photos app received crop and rotate abilities, networked drive and Desktop mode support, and auto-curated collage slideshows. In the Video app, you can watch with closed captioning, purchase in local currencies, and search by actor or director. The Music app gets expanded music services, a SmartDJ feature for hands-free music discovery, and an improved "now playing" experience.

Previously, the Bing-powered apps were fairly solid, if a bit light on features. That's no longer the case. The Maps app is the opposite of Apple's: gorgeous, easy to use, powerful, and accurate. It now has a "bird's eye view" option, more than 3,000 indoor maps, driving direction hints, improved customization, and integration with Bing and Travel apps.

The Finance, Sports, Travel, Weather, and News apps now support videos, and pull in more news and magazine content. There's more specialized content, so the Finance app supports more market exchanges and the Sports app grabs scores and stats from more leagues. The Travel app can show you 360-degree panoramas, and the News app gets better offline reading and better article reading support.

Screenshot by Seth Rosenblat/CNET

The Bing search app integrates Bing rewards, offers richer results for local content, allows you to zoom on your search results to see related queries, and supports the Windows 8 file picker so you can use an image from Bing on your lock screen or in other apps.

Lastly, the Games app offers more games, and finally supports in-game purchasing -- previously a big concern for developers.

Microsoft, however, has more fixes to make. Windows 8 forums are filled with complaints about faulty webcam support, trouble with browser multitasking in Metro mode, and missing basic features in the core four productivity apps.