HTC EVO 4G and myTouch 4G Slide now supported by HTC Dev bootloader unlock tool - HTC Source
If you have an HTC device made prior to September 2011, you may now be able to unlock your bootloader using the official HTC Dev tool. HTC recently announced that it has added the EVO 4G (Sprint) and myTouch 4G Slide (T-Mobile US) to their list of supported devices. This brings the list of supported devices to 23. Don’t despair if you don’t see your device listed as they are frequently adding devices to that list. It should just be a matter of time before your device shows up.
Once you have that bootloader unlocked, you can start using custom ROMs that are available including the popular Cyanogen ROM. The customization options for your phone are now almost unlimited! Just keep in mind that using HTC’s official unlock tool may void your warranty.
Don’t forget to share with us how you have customized your newly unlocked phone. We’d love to see your creativity.
UPDATE: HTC now states that ALL devices made prior to September 2011 have bootloaders that are unlockable.
All HTC Android devices launched after September 2011 are unlockable. The website will be updated accordingly to reflect this in the coming weeks. We continue to work on models launched prior to September 2011, please check back often for the status of older devices.
Source: HTC Dev