Do you want a full DSLR or EVIL?
If you wanted full DSLR, there are a couple of choice, such as D3000 (and soon D3100), 1000D, Sony A350, A230, Pentax k-x, Olympus E 450 (I think), all of them are quite light weigh and small.
Other than that, you could check on the following mirrorless camera that are quite small (almost like compact point and shoot, except that they have big sensor and interchangeable lens),
1) Olympus E-PL1, EP1 (I don't know if this is still available), EP2
2) Panasonic's GF-1
3) Sony's NEX series
But as some had suggested, better to go down to the store and test out the camera yourself. Feel for it and see if you like it or not.
Happy hunting!