While IIRC this thread was rather about ca. 28mm scale minis, for those who might be interested in going 15mm regardless might find the up-and-coming Critical Mass a line worth watching:
http://www.criticalmassgames.com/ <-- EDIT: link fixed to their current URL
They've got the 3D design whiz John Bear Ross on board doing (at least some of) the vehicles, and the previewed greens of the infantry look quite good too. Here's some piccies of those:
http://dropshiphorizon.blogspot.com/2009/07/critical-mass-games-arc-fleet-wip.html
There's something rather "Defianceish" about some of their models, most notably the humans...
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Meanwhile back in the (apparently all of a sudden less fashionable) 28mm scale world...
This was initially anounced in April, but is now picking up steam for an actual launch... AE-Bounty from Darkson Designs (known for their alt-WWII game) features some ca. 28mm scale alien minis (as well as the perquisite humans). These are described as "retro/comic/Star Wars" in style and frankly the aliens I've spotted so far are, well, just too silly for me. Previewed human (or mutated human, as the case might be) models look nice tho and a promise has been made of many opportunities to custom you minis, which might indicate they are going to sell bitz from the line... Anyway, here's the official board where you can go to dig up pix:
http://darksondesigns.proboards.com/index.cgi?board=bountyinfo
Whilst on the subject of retro/comic, Newbold have circulated their scifi dragonoids, the Grak, back into their charity shoppe:
http://www.newboldworld.com/09CS1/index.html
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Incidentally, both CM and AE-B are going to have an associated game available but I'm sure nobody here will want to bother about those