Yes. Had to look it up, because all I could remember was the Vanguard mutual fund ticker, VGSLX. The ETF equivalent is VNQ; ER of 0.12%. Fidelity is FREL; it's got an even lower expense ratio of 0.08%.
I should note here that I am still far from retirement--even ER--so I am worried about setting up a well-diversified asset allocation that I can stick with for the next 20+ years. I'm also worried more about growth & accumulation than about capital preservation, so if any particular asset class takes a beating next month, it doesn't bother me. In fact, I'll buy more
Regarding REITs, YMMV depending on where you're at in life. A retiree, or near-retiree, would be wise to be cautious with making REIT investments; maybe 5% or so if anything.
I'm personally considering a slightly larger proportion, because bonds are likely to be a huge drag on my portfolio for the foreseeable future.
In looking at VNQ it looks like since inception in 2004 it's up ~7.5% annually. If my research is correct that is roughly half what the S and P has done over that time.
And yes, if you're 20+ years out from retirement you'd be very wise to consider 100% equity.