UPDATE: Snake found, alive and well.
This just in from Craigslist:
penelope- lost snake (T-between park and andrew)
she is a very mellow snake- never hisses or bites and is very timid. she is a bit under 3 feet long with a brownish, almost pinkish paisley looking pattern on her back. she is 3 years old and ive had her since she was 5 days old. if you see her, if you find her- please call me @413-530-6350 ANYTIME. you will be rewarded and will also be a hero. please help!
The Globe interviews the snake lady, who said "she is accustomed to taking Penelope everywhere, and was wearing her around her neck, concealed by a scarf, when she boarded the T Thursday."