The Scott catalogue number for this issue is 5256.

From the USPS; further updates will appear after the initial, introductory entry:

Meyer Lemons Meyer Lemons is a 2-cent definitive stamp. The stamp art features a whole Meyer lemon next to two wedges of the cut fruit.

This stamp will be issued January 19th in Kenner, Louisiana. That coincides with the Winter Stamp Fest & Postcard Show.

Updated December 21st from the Postal Bulletin:

On January 19, 2018, in Kenner, LA, the U.S. Postal Service® will issue the 2-cent denominated Meyer Lemons stamp, in one design, in a pressure-sensitive adhesive (PSA) coil of 10,000 stamps (Item 760400). The stamp will go on sale nationwide January 19, 2018.

The Meyer Lemons stamp is a new 2-cent definitive stamp that features a whole Meyer lemon next to two wedges of the cut fruit. The illustrations were created with pen and ink and watercolor. Art director Derry Noyes designed the stamp with an existing illustration by John Burgoyne.

Availability to Post Offices: Item 760400, 2-cent Meyer Lemons PSA Coil of 10,000 Stamps
Stamp Fulfillment Services (SFS) will not make an automatic push distribution to Post Offices™.
How to Order the First-Day-of-Issue Postmark:
Customers have 60 days to obtain the first-day-of-issue postmark by mail. Each cover must have sufficient postage to meet First-Class Mail® requirements. They may purchase new stamps at their local Post Office, at The Postal Store® website at usps.com/shop, or by phone at 800-782-6724. They must affix the stamps to envelopes of their choice, address the envelopes (to themselves or others), and place them in a larger envelope addressed to:

FDOI – Meyer Lemons Stamp
USPS Stamp Fulfillment Services
8300 NE Underground Drive, Suite 300
Kansas City, MO 64144-9900

After applying the first-day-of-issue postmark, the Postal Service will return the envelopes through the mail. There is no charge for the postmark up to a quantity of 50. There is a 5-cent charge for each additional postmark over 50. All orders must be postmarked by March 19, 2018.

Technical details for the Meyer Lemons stamp will appear in a future edition of the Postal Bulletin.

Updated December 27th: Here is the pictorial first-day postmark: It measures 2.03” x 1.5”.

Updated January 5th, from the Postal Bulletin:

Philatelic products for this stamp issue are as follows:

• • 760416 First-Day Cover, $0.95.
  • 760415 coil strips of 500, $10.00 [added February 1]

Technical Specifications:

Issue: Meyer Lemons Stamp
Item Number: 760400
Denomination & Type of Issue: 2-cent Denominated, Mail-use
Format: Coil of 10,000 (1 design)
Series: N/A
Issue Date & City: January 19, 2018, Kenner, LA 70062
Art Director: Derry Noyes, Washington, DC
Designer: Derry Noyes, Washington, DC
Typographer: Derry Noyes, Washington, DC
Existing Photos: John Burgoyne, West Barnstable, MA
Modeler: Sandra Lane/Michelle Finn
Manufacturing Process: Offset, Microprint
Printer: Banknote Corporation of America
Printed at: Browns Summit, NC
Press Type: Alprinta 74
Stamps per Coil: 10,000
Print Quantity: 100,000,000 stamps
Paper Type: Nonphosphored Type III
Adhesive Type: Pressure-sensitive
Processed at: Banknote Corporation of America, Browns Summit, NC
Colors: Pantone 7413, Cyan, Magenta, Yellow, Black
Stamp Orientation: Vertical
Image Area (w x h): 0.73 x 0.84 in./18.54 x 21.34 mm
Stamp Size (w x h): 0.87 x 0.98 in./22.10 x 24.89 mm
Plate Size: 560 stamps per revolution
Plate Numbers: “B” followed by five (5) single digits
Coil Number Frequency: Plate numbers every 28th stamp below stamp image

Added February 1:
Collectors can order coil strips of 500 from Stamp Fulfillment Services (USPS.com or 800-STAMP-24). The order number is 760415.

Added January 17, 2019:
A 3,000-stamp coil was added, effective January 27th. It is item 750000.