I love getting shots of all the birds around where I work, but I freely admit I'm no birder and have a hard time identifying a lot of them (although I'm getting better). I took these yesterday and just loved the contrast of the colors. If I could post the larger ones, you'd see a lot more of the flowering currant and they really made a great environment.
Anyway - This appeared to me to be a Yellow Warbler, but the birders I know think it may be an Orange Crowned Warbler. I think they're right although I didn't get a good shot of the crown. Note the white rump though.