A spread of results from Medline for all who are interested (I should point out that I suspect that the 2nd study, looking at 7th day adventists, does the best job of controlling for relevant lifestyle factors). There are a lot more available if you search (Vegetarian, Diet) & (Mortality):
Key TJ. Appleby PN. Rosell MS. Health effects of vegetarian and vegan diets. [Review] [65 refs] [Journal Article. Review] Proceedings of the Nutrition Society. 65(1):35-41, 2006 Feb.
"Cohort studies of vegetarians have shown a moderate reduction in mortality from IHD but little difference in other major causes of death or all-cause mortality in comparison with health-conscious non-vegetarians from the same population. Studies of cancer have not shown clear differences in cancer rates between vegetarians and non-vegetarians... Overall, the data suggest that the health of Western vegetarians is good and similar to that of comparable non-vegetarians."
Fraser GE. Associations between diet and cancer, ischemic heart disease, and all-cause mortality in non-Hispanic white California Seventh-day Adventists. [Journal Article. Research Support, U.S. Gov't, P.H.S.] American Journal of Clinical Nutrition. 70(3 Suppl):532S-538S, 1999 Sep.
"The lifetime risk of IHD was reduced by approximately 31% in those who consumed nuts frequently and by 37% in male vegetarians compared with nonvegetarians. Cancers of the colon and prostate were significantly more likely in nonvegetarians (RR of 1.88 and 1.54, respectively), and frequent beef consumers also had higher risk of bladder cancer. Intake of legumes was negatively associated with risk of colon cancer in nonvegetarians and risk of pancreatic cancer. Higher consumption of all fruit or dried fruit was associated with lower risks of lung, prostate, and pancreatic cancers. Cross-sectional data suggest vegetarian Seventh-day Adventists have lower risks of diabetes mellitus, hypertension, and arthritis than nonvegetarians. Thus, among Seventh-day Adventists, vegetarians are healthier than nonvegetarians but this cannot be ascribed only to the absence of meat."
Appleby PN. Thorogood M. Mann JI. Key TJ. The Oxford Vegetarian Study: an overview. [Comparative Study. Journal Article. Research Support, Non-U.S. Gov't] American Journal of Clinical Nutrition. 70(3 Suppl):525S-531S, 1999 Sep.
"After adjusting for smoking, body mass index, and social class, death rates were lower in non-meat-eaters than in meat eaters for each of the mortality endpoints studied [relative risks and 95% CIs: 0.80 (0. 65, 0.99) for all causes of death, 0.72 (0.47, 1.10) for ischemic heart disease, and 0.61 (0.44, 0.84) for all malignant neoplasms."
Key TJ. Fraser GE. Thorogood M. Appleby PN. Beral V. Reeves G. Burr ML. Chang-Claude J. Frentzel-Beyme R. Kuzma JW. Mann J. McPherson K. Mortality in vegetarians and nonvegetarians: detailed findings from a collaborative analysis of 5 prospective studies. [Comparative Study. Journal Article. Meta-Analysis. Research Support, Non-U.S. Gov't] American Journal of Clinical Nutrition. 70(3 Suppl):516S-524S, 1999 Sep.
"Mortality from ischemic heart disease was 24% lower in vegetarians than in nonvegetarians (death rate ratio: 0.76; 95% CI: 0.62, 0.94; P<0.01).... There were no significant differences between vegetarians and nonvegetarians in mortality from cerebrovascular disease, stomach cancer, colorectal cancer, lung cancer, breast cancer, prostate cancer, or all other causes combined."