Well, after about 24 hours, and 30 miles later... the battery died again. Battery light brightened, ABS light came on, lights dim, and car died. AAA charged up my battery real good, and then followed me home. I made it just fine. Yup, sounds like the alternator to me too.
I've got it hooked up to a wall charger, on SLOW charge all night to be sure I can get to work in the morning (530 AM!!).
I'm taking it in Sunday.

Thanks.

BTW, anyone know how much an alternator is for my car?

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2006 E350 w/ 155k miles (Daily Driver)

Previous:
1993 300E 3.2L Sedan w/ close to about 300k miles
2003 E500 Brilliant Silver (Had 217k miles when totalled!)
1989 300E with 289,000 miles (had for <1 yr while in HI)
03 CLK 500 cabrio (Mom's)
2006 C230k (Dad's)
1999 S420 (Mom's/Dad's)
2000 C230k Sport sedans
2001 CLK320 Cabrio (Mom's)
1995 C280 My First Mercedes-Benz... (155k miles. EXCEPTIONAL AUTOMOBILE. Was Very hard to let go of!)