Joe Johnston confirmed that The Invaders will be in the second half of Captain America:First Avenger, he also confirmed that nine costumed characters will be in the Star Spangled Patriots film.
There are the 3 confirmed characters:
Captain America-Chris Evans
Bucky-Sebastian Stan
Union Jack-JJ Fields
The 2 rumored characters
Namor-David Boreanaz???
Golden Girl-Amy Smart(rumored)
Then we have 4 unknown characters my personal picks for the last ones are
The Original Human Torch-???
Toro-???
Spitfire-???
Silver Scorpion-???
Chris Evans (Captain America), Hugo Weaving (Red Skull), Tommy Lee Jones (Gen. Chester Philips), Sebastian Stan (Bucky), Stanley Tucci (Abraham Erskine), Hayley Atwell (Peggy Carter), Toby Jones (Arnim Zola), Dominic Cooper (Howard Stark), Neal McDonough (Dum Dum Dugan), Helen Mirren (Rumored), Nicholas Cage (Rumored), Bruce Willis (Rumored) and Samuel L. Jackson (Nick Fury).
Also Captain America: The First Avenger hits theaters July 22, next year in 3D.