Travelling on ALMOST expired passport?

Disclaimer- this happened 2 years ago.

I had a WP in old passport.  It expired, and so I applied for a new one.  The old passport was returned to me, and I travelled extensively for 18 months with both passports (old with visa, and new that was valid).  Never had an issue.

It's expensive to get the visa transferred.  (although perhaps worth it if it's a ILR).

A nifty thing the UK does- if you apply for a new passport, and the old one is still valid, they will put X number extra months on the new one.  I don't think the US does this.

Yep I do the same. My ILR is in my expired US passport so I have to travel with both and I know the UK accepts this. I am not spending £160 for a new visa sticker.
Trouble is the US Embassy website is not very forthcoming about visa queries so I have to call a premium rate number to try and speak to someone.

If she's going to renew she should probably do so using the expedited service.  I sent my passport off for renewal 2 weeks ago, and it still hasn't registered as being processed (though they have cashed the check. . .)  I wouldn't want to worry about it getting back in time going with the regular service.

This was admittedly a couple of yrs ago (and I don't know where I read this) but I remember reading somewhere that US and UK have some kind of a arrangement wherein passports that are valid for less than six months are valid for VWP purposes - but if it was me I would definitely renew my passport before travelling. Speaking of which - I also remember reading somewhere that you can book an emergency same-day passport-renewal appointment in one of the major passport processing centres as long as you have proof of immediate travel (i.e. air ticket for e.g.)

Sorry to be so vague but just wanted to put this out there and I'm willing to stand corrected.

This was admittedly a couple of yrs ago (and I don't know where I read this) but I remember reading somewhere that US and UK have some kind of a arrangement wherein passports that are valid for less than six months are valid for VWP purposes - but if it was me I would definitely renew my passport before travelling. Speaking of which - I also remember reading somewhere that you can book an emergency same-day passport-renewal appointment in one of the major passport processing centres as long as you have proof of immediate travel (i.e. air ticket for e.g.)

Sorry to be so vague but just wanted to put this out there and I'm willing to stand corrected.

Topic already covered.

Yes, BUT the UK is on the list of those exempt from this requirement.
http://www.state.gov/documents/organization/104770.pdf