Oh goodnes... I'm not sure what happened - I only meant to delete my original comment (because frankly it didn't have much to offer..) - but when I did - it deleted much of the discussion string that followed... My sincere apologies - I hope that what was lost could perhaps be resubmitted...
I honestly don't read a lot of steampunk fiction, but if you're looking for good Victorian lesbian novels the master is Miss Sarah Waters. There isn't anything particularly steamy (in our sense of the word) about her books, but Fingersmith, Affinity, and Tipping the Velvet are wonderful reads.
I have a serial of GLBT steampunk stories on my myspace page, look in the blogs of Royal Brotherhood of the Ether.
ALWAYS looking for contributions! Anybody like to write too? Come drop me a copy and I'll post it!
The character Judah Low in China Mieville's Iron Council, and his lover, Cutter.
I feel like there's others in Mieville's Bas-Lag series, but it's been a while since I read them and those are the two that spring to mind.
I can guarantee that my own works of fiction contain impressive amounts of both steam and sexually ambiguous characters of all flavours, but with my and my creative partner's dazzling (cynic button) pace of output, it may be quite some time before they are prepared for viewing.
This thread has been useful for the list of Steampunk works with queer references I'm compiling on tumblr. I assume I'm likely to find more in online fiction rather than published works, but I've only just started my exploration of specifically-Steampunk fiction so this is a great start.
I will add, without having read it (but with plans to do so): Wicked Gentlemen - Ginn Hale. It was given the prize of best novel in the 2008 Gaylactic Spectrum Awards.