Here's a summary with links to the weekly introduction notes on the Guardian Unlimited Arts Blog pages:
Week 1 - The Early Sonatas (
http://blogs.guardian.co.uk/music/2006/11/schiff_on_beethoven.html)
(1) Piano Sonata in F minor, opus 2 no. 1
(2) Piano Sonata in A major, opus 2 no. 2
(3) Piano Sonata in C major, opus 2 no. 3
(4) Piano Sonata in E-flat major, opus 7
Week 2 - Trio Sonatas from Op. 10 & Pathetique (
http://blogs.guardian.co.uk/music/2006/11/schiff_on_beethoven_part_2.html)
(1) Piano Sonata in C minor, opus 10 no. 1
(2) Piano Sonata in F major, opus 10 no. 2
(3) Piano Sonata in D major, opus 10 no. 3
(4) Piano Sonata in C minor, "Pathétique", opus 13
Week 3 - Five Sonatas (
http://blogs.guardian.co.uk/music/2006/11/schiff_on_beethoven_part_3.html)
(1) Piano Sonata in G minor, opus 49 no. 1
(2) Piano Sonata in G major, opus 49 no. 2
(3) Piano Sonata in E major, opus 14 no. 1
(4) Piano Sonata in G major, opus 14 no. 2
(5) Piano Sonata in B-flat major, opus 22
Week 4 - Working Toward "Pastoral" (
http://blogs.guardian.co.uk/music/2006/11/schiff_on_beethoven_part_4.html)
(1) Piano sonata in A-flat major, opus 26
(2) Piano sonata in E-flat major, opus 27 no. 1
(3) Piano sonata in C-sharp minor, opus 27 no. 2 ('Moonlight')
(4) Piano Sonata in in D major, opus 28 ('Pastoral')
Week 5 - "Waldstein" (
http://blogs.guardian.co.uk/music/2006/11/schiff_on_beethoven_part_5.html)
(1) Piano sonata in G major, opus 31 no. 1
(2) Piano sonata in D minor, opus 31 no. 2 ("Tempest")
(3) Piano sonata in E flat major, opus 31 no. 3
(4) Piano sonata in C major, opus 53 ("Waldstein")
Week 6 - "Apassionata" and others (
http://blogs.guardian.co.uk/music/2006/12/schiff_on_beethoven_part_six.html)
(1) Piano sonata in F major, opus 54
(2) Piano sonata in F minor, opus 57 ("Apassionata")
(3) Piano sonata in F sharp major, opus 78
(4) Piano sonata in G major, opus 79 ("Cuckoo")
(5) Piano sonata in E flat, opus 81a ("Les Adieux")
Week 7 - "Hammerklavier" and others (
http://blogs.guardian.co.uk/music/2006/12/schiff_on_beethoven_part_seven.html)
(1) Piano sonata in E minor, opus 90, no. 27
(2) Piano sonata in A major, opus 101, no. 28
(3) Piano sonata in B flat major, opus 106 ("Hammerklavier")
(4) Piano sonata in B flat major, opus 106 ("Hammerklavier") cont'd
Week 8 - The Final Works (
http://blogs.guardian.co.uk/music/2006/12/schiff_on_beethoven_final_part.html)
(1) Piano sonata in E major, opus 109
(2) Piano sonata in A flat major, opus 110
(3) Piano sonata in C minor, opus 111