Historically, United has deposited the six systemwide upgrades earned for achieving or reqaulifying for 1K status at the beginning of the calendar year after which you achieve the status. So if you earn 1K status on August 1, 2010, you would receive your six systemwide upgrades on January 1, 2011, at which point they’re valid for 12 months.
It seems that they have changed that policy as of this year, now depositing the six systemwide upgrades immediately upon earning 1K status, and the systemwide upgrades are still only valid for a year. So if you achieved 1K status today, for example, your systemwide upgrades would likely post within a week or so, and would be valid through March, 2012. Historically, in comparison, you would receive them in January, 2012, and they would be good through January, 2013.
This can be either good or bad news depending on your future travel plans. I know many people prefer American’s system, as they deposit systemwide upgrades immediately upon earning Executive Platinum status, and they’re always valid until February two calendar years later. In other words, if I qualified for Executive Platinum status today, my systemwide upgrades would be valid until February 2013.
It’s worth keeping in mind that as of a couple of weeks ago, you can link your United and Continental frequent flyer accounts. If you have elite qualifying miles in both programs and are close to requalifying for 1K, it probably makes sense not to link your accounts yet, as that will only cause you to cross the threshold faster, making your systemwide upgrades expire sooner.