Last month the upgraded Butterfly S got the last version of Jelly Bean and the shiny new Sense 5.5 UI, and it looks like HTC's software team has worked their way to the original Butterfly model. Noted HTC leaker @LlabTooFer posted the over-the-air update screen this morning, and at least one blog showed the same software update going out in Malaysia yesterday. According to a Twitter reply, the Taiwanese variant is being updated as well.
Get excited: HTC just dropped the kernel source for three handsets (admittedly, very late). Specifically, the HTC Butterfly, Desire SV, and One VX.
You can head over to HTC's developer website to pick up the files now. For the Butterfly and One SV, there are multiple packages for available for various regions.