Please note, only US English is available at this time. I will update this thread with access to other languages. Also note, these links might not be live yet. I am not trying them, because I don't want to eat up my bandwidth by opening the link (metered connection). IE has a tendency to anticipate a download.
If you can't wait on Microsoft to push .ISO files to testers for build 10049, you can create yours now:
Download the desired edition and architecture from the following link:
Windows 10 Pro x86 build 10049 Windows 10 Pro x64 build 10049 Windows 10 Enterprise x86 build 10049 Windows 10 Enterprise x64 build 10049
UPDATE: I have decided to retire these links because they are not working. Microsoft is strongly pushing Windows Update for installing build 10049.
The Windows Team is deciding whether to release official ISO files the week of April 12, 2015.
For persons requesting other languages, see the following thread:
I will update this link when they become available.
Download ESD Decrypter 4.7 (esd-decrypter-wimlib-4.7z)
You can use NTLite as an alternative to convert the .ESD file into a .ISO:
Extract esd-decrypter-wimlib-4.7z to a folder.
Put the appropriate .ESD file you downloaded into that same folder.
Right click decrypt file in the same folder and click Run as administrator
Select option 1
When complete, burn to a blank DVD or create a bootable copy on a USB thumbdrive.
See article for instructions how to do that.
Persons have recommended using Rufus for best results when creating a bootable copy on a USB thumb drive.