Pretty similar to previous deals although now $USD5 cheaper than last time.
Is also free to play until Sunday 1pm PDT.
Based on commentary I've seen the key part is to get the Gods and Kings expansion in addition to the base game - which is included in the Gold Edition.
Can also get the Gold Edition upgrade for $USD5 through the same link (further down the page).
Looks to be basically all advertising for the upcoming Brave New World Expansion.
EDIT: see below note from tabz re GMG:
tabz 6 hours 18 min ago
greenmangaming is also 75% off Civ V products and works out to be cheaper than getting it directly from Steam:
http://www.greenmangaming.com/civilization-v/
Normal Edition: $7.49 USD ($17.49 on Steam)
Gold edition: $12.49 USD ($22.49 on Steam)
Not sure if this 20% off coupon code is still valid, but it worked last week: GMG20-JLKSA-7A8HA
Isnt the gold edition technically Civ 5 GOTY + Gods and Kings?