Thought I'd present a total of SC stalls at this point and update as necessary, 'cause it's getting way too tedious to type them all in repeatedly. The states are listed in the order they appear on the official web page, alphabetically but divided roughly west of the Mississippi first, then east. I've only included those which appear on the web page, leaving off some that are known to be open but not yet listed.
Tesla Supercharger # of states/locations/stalls as of 5/20/2014: 30/94/593
Arizona
Buckeye 8
Flagstaff 4
Gila Bend 8
Holbrook 4
Kingman 6
Quartzsite 8
Yuma 8
Total: 7/46
California
Atascadero 8
Barstow 4
Buellton 8
Corning 6
Folsom 4
Fremont 8
Gilroy 10
Harris Rch. 7
Hawthorne 6
Mt. Shasta 4
Roseville 7
San Juan Capistrano 7
Tejon Rch. 6
Vacaville 8
Total: 14/93
Colorado
Glenwood Springs 6
Grand Junction 6
Lone Tree 4
Silverthorne 8
Total: 4/24
New Mexico
Farmington 4
Gallup 4
Total: 2/8
Nevada
Las Vegas 6
Total: 1/6
Oregon
Detroit Lake 6
Grant's Pass 4
Springfield 8
Woodburn 8
Total: 4/26
South Dakota
Mitchell 6
Murdo 4
Rapid City 4
Total: 3/14
Utah
Beaver 4
Blanding 4
Green River 4
Moab 4
Richfield 4
Total: 5/20
Washington
Burlington 8
Centralia 10
Ellensburg 5
Ritzville 4
Total: 4/27
Wyoming
Cheyenne 4
Lusk 4
Total: 2/8
Connecticut
Darien N/S 8
Greenwich N/S 8
Milford N/S 4
Total: 3/20
Delaware
Newark 4
Total: 1/4
Florida
Fort Myers 8
Port Orange 6
Port St. Lucie 8
St. Augustine 6
Total: 4/28
Georgia
Macon 8
Savannah 6
Total: 2/14
Illinois
Aurora 4
Highland Park 4
Normal 4
Rockford 6
Total: 4/18
Indiana
Angola 6
Mishawaka 6
Total: 2/12
Maryland
Bethesda 2
Hagerstown 6
Total: 1/6
Michigan
St. Joseph 8
Total: 1/8
Minnesota
Albert Lea 4
Worthington 6
Total: 2/10
North Carolina
Burlington 8
Lumberton 4
Plymouth 8
Rocky Mount 8
Total: 4/28
New Jersey
Hamilton Township 6
Total: 1/6
New York
Albany 3
JFK Int. 4
Syosset 4
Total: 3/11
Ohio
Macedonia 6
Maumee 6
Total: 2/12
Pennsylvania
Cranberry 6
Somerset 6
Total: 2/12
Rhode Island
East Greenwich 8
Total: 1/8
South Carolina
Santee 6
Total: 1/6
Texas
Columbus 6
Corsicana 6
Huntsville 6
San Marcos 5
Waco 8
Total: 5/31
Virginia
Glen Allen 8
Woodbridge 4
Total: 2/12
Wisconsin
Eau Claire 6
La Crosse 6
Madison 3
Mauston 6
Pleasant Prairie 8
Total: 3/15
West Virginia
Triadelphia 4
Total: 1/4
Edit: Per the 'Tesla Supercharger Confirmed' topic in the TMC forum as well as photos, corrected # of stalls at Hawthorne from 4 (as shown on Tesla's SC page) to 6, and also updated the Ca. and absolute totals from 12/77 to 12/79, and from 460 to 462.
Eau Claire, WI, with 6 stalls, and the temp site at Bethesda, MD, with 2 are now listed, so trips between Chicago-Twin Cities and Glen Allen-Newark are now doable in winter by S-60s.
As of 2/4/14, Yuma, AZ with 8 stalls is officially online. As expected, the rate of new SCs coming online has dropped off considerably since the X-C route was completed. While they don't have to maintain the pace of 23 SCs they brought online in January, Tesla will need to average about 15/month for the rest of the year if they are to meet the 'by 2014' map total.
As of 2/13/14, Pleasant Prairie, WI is listed and mapped, so 75.
As of 2/20/14, Las Vegas, NV with six stalls is listed and mapped. Nevada is out of alphabetical order because Tesla's Supercharger website lists alphabetically by state abbreviation, and I wanted to use the same order here. I wonder which location will get them to 500?
As of 2/24/2014, Aurora, IL west of Chicago with 4 stalls is listed and mapped, total now 77. No one knew about this one. One more location should get them to 500 stalls.
As of 2/28/14, Lone Tree, CO with 4 SC stalls is listed and mapped, total now 78 with 500 stalls.
As of 3/11/14, Plymouth, NC with 8 stalls is listed and mapped, total now 79. They were talking about opening one SC per workday this year, so they're well behind that pace since they finished the first transcontinental route. Who knows how much of that is due to the heavy winter, and how much to other factors.
As of 3/16/14, Green River, UT with 4 stalls is listed and mapped, total now 80.
As of 3/20/14, Buckeye, AZ with 8 stalls is finally online.
As of 3/25/14, Greenwich Ct. N & S with 4 each direction for a total of 8 are listed and mapped.
As of 4/7/14, Richfield, UT with 4 and Cranberry, PA (at last) with 6 stalls are now listed and mapped. Salt Lake City is 161 miles from Richfield, so easy in an 85 and doable with care in a 60. Las Vegas is 285 miles so still not possible, until St. George (for 85s) plus Beaver for 60s open. But they're getting close to eliminating the wholly unnecessary backtracking loop through SE Utah, into NM and then Arizona for people transiting, cutting almost 300 miles off the route from Grand Junction, CO to LA.
As of 4/15/14, Beaver, UT with four stalls is listed and mapped. 85s going transcontinental westward can probably now avoid the detour through New Mexico and Arizona, at least in good conditions, but those going eastward will probably need to drive very slowly and carefully if they try it, as it's 220 miles and 4,500+ feet of climb from Las Vegas.
As of 4/22/14, Hamilton Township, NJ with six stalls is listed and mapped. They really need to pick up the pace now that winter's past, as the year's almost 1/3rd over and they've only been averaging about 1 SC/week since they finished the initial transcontinental route, instead of the 1 SC/workday pace they intended to achieve for the year.
As of 4/30/14, Roseville, Ca with 7 stalls is finally open, to sighs of relief from Bay Area Model S owners who will no longer have to detour through Folsom when heading up to the North Tahoe and Reno areas.
As of 5/3/14, Woodbridge, VA with 4 and Albany, NY with 3 stalls are listed and mapped.
As of 5/7/14, the long delayed and eagerly awaited San Juan Capistrano, CA with 7 plus Triadelphia, WV with 4 stalls are listed and mapped (SJC actually went live yesterday).
As of 5/8/14, Macon, GA with 8 stalls is open, but not yet listed or mapped after one week, so I'm putting it here anyway [Edit: listed and mapped 5/15/14].