I want to thank everyone who posted their reccommendations. The information is very helpful. I especially found helpful Paige's link to the backpacking BBS at
http://www.backpacking.net/bbs.html. If you haven't had a chance to surf through, I strongly reccommend it for its wealth and breadth of information.
I want to follow up on my initial post by providing my definitions for free standing and three season tents. By free standing I mean a tent that does not require stakes or some other means of anchoring to the ground to retain its basic shape. Most dome tents with curving tent poles would fall into this category. The old style "A" tents that had a single pole in front and back would be a classic example of a non-free standing tent. My search showed me that the most common type of tent appears to be a dome variation that typically requires some grond anchoring to stake out the fly and there are few truly free standing tents available. This criteria is more a matter of degree than an absolute. The primary advantage of a free standing tent is that it may be pitched on surfaces such as granite the preclude the use of tent stakes. The disadvantage is that the more free standing a tent becomes (the fewer anchors it needs to retain its shape) the heavier the typical weight becomes due to extra poles, clips, and sleeves.
By three season tent I meant a tent that was not designed for the harsh conditions of winter. In theory all tents can be used year round, but some tents are better suited for stronger winds, heavier snow loads, and colder tempatures than others. Mountaineering, alpine, or four season tents are generally heavier and more expensive than their three season siblings.
My question about tents was prompted by a late season opportunity on Whitney for a multi-day trip. The fly on my 15 year old Sierra Designs Half Moon was put away wet by someone who borrowed it and the urethane coating is now gummed beyond repair. Sierra Designs does not have replacement flies for that model available, but they will sell me any of their tents at cost. For that reason I am leaning towards their Clip Flashlight. Since I've found a tent for use on our upcoming trip I will postpone my tent selection until the holiday season.
Many people reccommended the REI Half Dome Plus. It is a great tent. I've slept in one and think few tents achieve a similar functionality in that price range. It is very similar to the Half Moon I owned.
For others looking for light weight shelters my research turned up these options:
http://www.biblertents.com/2002/itent_eldo.html(expensive, but light four season free standing tent)
http://www.integraldesigns.com/tents-frame.htm(the also make incredibly lightweight tarps. Given that many people now carry hiking staffs, why not put them to use as tent poles under one of these tarps? At 8 oz for a tarp, it makes a great vesibule extension when rain has you stuck in your tent.)
http://www.hilleberg.com/Catalog/nallo_2_339317.htm(expensive and hard to find, but may be the lightest two wall tent out there. Their 3 person tent weighs less than most two man tents.)
I'd also suggest a quick look at
http://www.sixmoondesigns.com/ and Go-Lite's Den. Both of these shelters are a little to minimalist for me, but they may be the right thing for someone else.