Microsoft today has released ISO images for the latest Windows 10 Insider Preview build, 15025, which was released to the Fast ring two days ago. This is actually the second round of Insider Preview ISOs in a row that was published without the build first being offered to the Slow ring. The first was 15002, and that was a break from tradition.
Today also marks the beginning of the final Bug Bash for the Creators Update. The event will focus on build 15025, so naturally, Microsoft wants to make it accessible to as many Insiders as possible. There will also undoubtedly be quests that involve the new out-of-box experience, so a clean install would help you in testing that.
Just in case it doesn't go without saying, the ISO images are for the PC build only. Microsoft doesn't provide images for Windows 10 Mobile and if it did, it also hasn't released an easy way to flash them. You can download the 15025 ISOs, as well as the 15002 images, right here.