The 60k offer has definitely been extended - but there's definitely a small, new twist. Here's my story:

I applied for the card using the 60k banner on the United website on 2/25, and was instantly approved. Card was received on 3/1, and I activated it and began using it.

Last night, I received TWO identical looking printed offers in my (physical) mailbox - normally I just toss this stuff, but I figured I'd open it up to see the new expiration date on the offer.

One mailer was the standard offer as we all know it - "60k Offer" that is 50k miles on first use, 10k miles at $25k annual spend.

The second offer is a "65k Offer" - 50k miles on first use, 10k miles at $25k annual spend, and an extra 5,000 miles for adding a second authorized card within the first two months. Here's a scan of the printed offer (.jpg).

Both offers list the same expiration date - April 23, 2012.