Today, it was announced that SSHD:TSE will be definitely released on XBLA. I always thought it was anyway, but apparently it was only going to be put on the PC due to a relatively small fanbase on the 360, and not many people actually buying it. It's a real shame that ignorant fools shun SSHD as it isn't Call of Duty, but I don't care - It means I don't have to deal with them when I'm playing online.
But anyway, SSHD can also be pre-ordered now via Steam (which is coming to the Mac soon :D) and is available on the 28th of April, with the Xbox version coming out later. I don't know when exactly... Croteam hasn't told me.
And, SSHD:TSE will also have a load of new online modes, improving on the first's co-op only, and will have Deathmatches and various other gametypes, as well fantastical HD-ness.
...And now, we wait...