Apple today updated several applications, making them compatible with iOS 8.
Check the list below:

Version 2.2 of Podcasts includes several minor performance improvements and adds support for iOS 8.

This version of the Find iPhone app is compatible with iOS 8 and Family Sharing.

Remote 4.2.1 includes several small performance improvements and adds compatibility with iOS 8.

iTunes U
in Apple
Version 3.7.4 (40.3 MB) Requires iOS 11.0 or superior
iTunes U 2.1 adds iOS 8 compatibility and can add task due dates to your calendar automatically.

This version of the Find My Friends app includes support for iOS 8 and allows users to move their list of friends to their iCloud account, if necessary.

ITunes Movie Trailers 1.4.1 includes several minor performance improvements and adds support for iOS 8.
In addition to Apple, several renowned developers and companies have already updated their apps to support the new system, such as Instagram, Hyperlapse, Facebook, Facebook Page Manager, Google Maps, 1Password, Vimeo, WhatsApp Messenger, Pocket, Dropbox and Paper (from Facebook).
Update · 09/18/2014 s 19:38
A few more Apple apps updated to iOS 8:

Compatibility with iOS 8.

Compatibility with iOS 8.
Sorry, app not found.
Apple Configurator 1.6 contains improvements and bug fixes, including:
- Devices are wiped before restoring a backup.
- Compatibility with payloads and adjustments to new configuration profiles introduced in iOS 8.
- Content Filter: plug-in filter type.
- Domains.
- Email and Exchange: control to switch S / MIME encryption per message.
- Restrictions: Allow Handoff, Allow synchronization via iCloud in managed applications, Allow backup of business books, Allow synchronization of notes and highlights in business books.
- Restrictions (supervised only): Allow deletion of all content and adjustments, allow configuration of restrictions, allow Internet results in Spotlight.
- VPN: connection type IKEv2 and VPN Always Enabled.
In addition to them (from Apple), other celebrities like Instapaper, Carousel, Clear, Kindle, Scanner Pro, Calendars 5, Printer Pro, PlayKids and Prizmo have also been updated to add support for iOS 8.