[HTC Aria Android Development] modest_mandroid:
I think some trouble shooting comments should be mentioned, so I'll just write a few things I noticed while rooting my device (for 7 frustration filled hours).

If you cannot see your device show up in 'adb devices' in recovery, boot into the OS normally and see if it shows up. If it does not, then it's a safe bet that you have one of two problems - you do not have all the drivers installed, or you do not have 'usb debugging' enabled. This can be enabled in 'settings->applications->development->usb debugging'. To avoid driver issues, it's highly recommended that you do this process in linux or osx.

If, on the other hand, your phone DOES show up in Android but not in recovery, or if it just blips on the screen for a second (when running the loop) as an offline device, then it might be the formatting of your sd card. Do NOT format your sd card from your phone or within Android. The ONLY time I managed to get the phone to show up in recovery without disappearing immediately was by removing the sd card, formatting it in windows or osx with an external card reader, copying the files over (new rom or rooting files), and then replacing it in the phone while the phone is off. After putting the card back in your phone, try the procedure again - go to the bootloader->hboot->recovery (while the cable is unplugged), then press the power button and immediately after plug the cable in (usually works when you plug the cable in about .2-.5 seconds later). If it does not show up at all, reboot the phone and try again, but do NOT let it boot back to Android. You can get back in to the bootloader by waiting until the 'HTC quietly brilliant' screen shows up and typing 'adb reboot bootloader' with the usb cable attached.

It took me a really long time to figure that out. I don't think the type of sd card matters so much as the formatting of it. I actually used the 2gb card that came with the phone, and it worked almost every single time after I reformatted the card.

Also, if you manage to get it working and root the phone, do yourself a huge favor and install the custom Unrevoked recovery image mentioned in the original rooting thread, so you never have to deal with this nonsense ever again.

Also also, if you get to the step where you do 'adb push ota.zip /sdcard/update.zip' and you get an error:0, installation aborted message, you did something wrong. The problem is that you aren't actually supposed to flash ota.zip. What you're supposed to do is push ota.zip to your phone as update.zip, and leave it there. Don't touch anything else. What you will do after that is type 'adb push update.zip /sdcard/update.zip' in the command prompt (WITHOUT hitting enter yet, just get ready to). You will then select 'sdcard:update.zip' and press power and IMMEDIATELY AFTER pressing power, you will press enter on the command prompt to execute your adb push command. What this does is causes recovery to read the ota.zip file you uploaded and recognize it as a legit update, but you replace it with update.zip before it actually gets extracted (if your timing is good). So recovery reads the signature of ota.zip, but actually extracts the stuff in update.zip and runs that instead.

Hope that helps with some common problems I observed. Good luck, dudes.