I bought a Marmot Precip Jacket and some full side-zip precip pants last year on ebay. They were my reaction to poncho-failure the summer before (July 12, 2008 storm...) that was scary dangerous in terms of possible hypothermia.
It only rained a few times last summer, but the precip gear worked very well for those days. Pants went on in no time and the jacket was very well vented. In spiteof rather warm temps when it rained, even sun peaking out on and off, I was able to keep moving up to Whitney (west side) without too much sweat.
In the past I carried GoreTex from Schoeffel, a German brand. A totally bulletproof jacket I bought in 1986 and have worn almost daily in Wisconsin Winters and on climbing trips. I think for summer Sierra use, the prcip beats this Jacket, mostly because it weighs half as much and does what it is intended for. I also used it in late September last year, when it was rather cold (10 degrees Trail Camp morning) and combined with my trusty North Face Denali Fleece, it was still plenty warm.
Can't beat the $40 I paid for each on ebay either...