Earlier this year, I ordered the 17-85IS during one of the Dell deals. Total price, including tax, was $460. I also got a bunch of e-mails saying that the item is backordered, you must respond to this e-mail or we will cancel the order, etc.
I responded to the e-mails to keep the order open. Got the lens after a one month wait.
Not long after, I ordered the 10-22, also with a Dell deal. Total price was $640. Had it in 2 days.
Last week I ordered a 10-22 for my gf. Total price was $567 (no tax where she lives). Right now my status page says on backorder, estimated shipping date is 8/29. If this order gets delayed, and doesn't ship for a month or two or three, it's no problem, simply because the lens is not a "I must have it now" thing. She has a 20D, a 300 f/4 L IS, and a 100-400 L IS to keep her busy, all of which I bought for her (hey, she's my baby ).
Her interest is in bird photography, so the 10-22 is for those "Oh boy, I'm glad I had that lens with me" occasions. May not get a whole lot of use for a while, but at that price, it's worth waiting for. And we'll have plenty of photo ops in the near future to use it (building a new house in Florida; lots of places for great pictures there).
Remember, Dell sells this stuff through a 3rd party distributor. When these deals come up, they must get a ton of orders for them. The smart thing to do is pull the item from the web site until they get caught up with the backlog. The 10-22 has been on and off the Dell site numerous times. If you missed it this time, don't worry, it'll be back with more sales, coupons, etc.
Now, go out and take pictures with the stuff you already have, and have fun!
20D, 30D, 500f/4L IS, 300f/4L IS, 300f/2.8L IS, Canon 1.4TC, Canon 2xTC, 70-300IS, 17-85IS, EFS 10-22, Sigma 150 Macro, 3021PRO, RRS BH-40LR, Gitzo 1325, full Wimberley Head v2, Wimberley Sidekick, and a bunch of other stuff.