It looks like the folks at Mozilla have done it again. Thunderbird 0.6 has been released with some degree of fanfare in late April. It has improved junkmail filtering and a swizzy new logo. Please note that if you’re using a theme that was created for older versions of this product, you may need to update it. The installer apparently doesn’t know this, so you may lose some functionality unless you switch back to the default theme. Enjoy!