[Android Q&A, Help & Troubleshooting] IQAndreas:
When I look inside /dev/block, I see a lot of partitions on mmcblk0 (and I have confirmed, just to be certain, the combined size of all partitions almost exactly equals the size of mmcblk0 on its own):

~ # ls mmcblk0*
mmcblk0
mmcblk0p1
mmcblk0p10
mmcblk0p11
mmcblk0p12
mmcblk0p13
mmcblk0p14
mmcblk0p15
mmcblk0p16
mmcblk0p17
mmcblk0p18
mmcblk0p19
mmcblk0p2
mmcblk0p20
mmcblk0p21
mmcblk0p22
mmcblk0p23
mmcblk0p24
mmcblk0p25
mmcblk0p26
mmcblk0p27
mmcblk0p28
mmcblk0p29
mmcblk0p3
mmcblk0p30
mmcblk0p31
mmcblk0p32
mmcblk0p33
mmcblk0p4
mmcblk0p5
mmcblk0p6
mmcblk0p7
mmcblk0p8
mmcblk0p9

What is even more bizarre is I get even more partitions listed when I use fdisk:

~ # fdisk -l -u /dev/block/mmcblk0
Warning: deleting partitions after 60

Disk /dev/block/mmcblk0: 2432 MB, 2432696320 bytes
1 heads, 16 sectors/track, 296960 cylinders, total 4751360 sectors
Units = sectors of 1 * 512 = 512 bytes

Device Boot Start End Blocks Id System
/dev/block/mmcblk0p1 * 1 1000 500 4d Unknown
Partition 1 does not end on cylinder boundary
/dev/block/mmcblk0p2 1001 1128 64 45 Unknown
Partition 2 does not end on cylinder boundary
/dev/block/mmcblk0p3 1129 10128 4500 46 Unknown
Partition 3 does not end on cylinder boundary
/dev/block/mmcblk0p4 10129 4751358 2370615 5 Extended
Partition 4 does not end on cylinder boundary
/dev/block/mmcblk0p5 10130 70129 30000 49 Unknown
/dev/block/mmcblk0p6 70131 95130 12500 50 Unknown
/dev/block/mmcblk0p7 95132 99227 2048 51 Unknown
/dev/block/mmcblk0p8 99229 105372 3072 52 Unknown
/dev/block/mmcblk0p9 105374 109469 2048 53 Unknown
/dev/block/mmcblk0p10 109471 111518 1024 54 Unknown
/dev/block/mmcblk0p11 111520 113567 1024 56 Unknown
/dev/block/mmcblk0p12 113569 131071 8751+ 55 Unknown
/dev/block/mmcblk0p13 131073 139264 4096 4a Unknown
/dev/block/mmcblk0p14 139266 147457 4096 4b Unknown
/dev/block/mmcblk0p15 147459 149506 1024 74 Unknown
/dev/block/mmcblk0p16 149508 163326 6909+ 75 Unknown
/dev/block/mmcblk0p17 163328 163839 256 76 Unknown
/dev/block/mmcblk0p18 163841 165888 1024 47 Unknown
/dev/block/mmcblk0p19 165890 167937 1024 34 Unknown
/dev/block/mmcblk0p20 167939 170498 1280 36 Unknown
/dev/block/mmcblk0p21 170500 187901 8701 71 Unknown
/dev/block/mmcblk0p22 187903 196094 4096 48 Unknown
/dev/block/mmcblk0p23 196096 196607 256 73 Unknown
/dev/block/mmcblk0p24 196609 200702 2047 26 Unknown
/dev/block/mmcblk0p25 200704 1835006 817151+ 83 Linux
/dev/block/mmcblk0p26 1835008 3833854 999423+ 83 Linux
/dev/block/mmcblk0p27 3833856 4095998 131071+ 83 Linux
/dev/block/mmcblk0p28 4096000 4452350 178175+ 83 Linux
/dev/block/mmcblk0p29 4452352 4456446 2047+ 33 Unknown
/dev/block/mmcblk0p30 4456448 4504942 24247+ 19 Unknown
/dev/block/mmcblk0p31 4504944 4505085 71 90 Unknown
/dev/block/mmcblk0p32 4505087 4505598 256 23 Unknown
/dev/block/mmcblk0p33 4505600 4702191 98296 c Win95 FAT32 (LBA)
/dev/block/mmcblk0p34 10130 70129 30000 49 Unknown
/dev/block/mmcblk0p35 70131 95130 12500 50 Unknown
/dev/block/mmcblk0p36 95132 99227 2048 51 Unknown
/dev/block/mmcblk0p37 99229 105372 3072 52 Unknown
/dev/block/mmcblk0p38 105374 109469 2048 53 Unknown
/dev/block/mmcblk0p39 109471 111518 1024 54 Unknown
/dev/block/mmcblk0p40 111520 113567 1024 56 Unknown
/dev/block/mmcblk0p41 113569 131071 8751+ 55 Unknown
/dev/block/mmcblk0p42 131073 139264 4096 4a Unknown
/dev/block/mmcblk0p43 139266 147457 4096 4b Unknown
/dev/block/mmcblk0p44 147459 149506 1024 74 Unknown
/dev/block/mmcblk0p45 149508 163326 6909+ 75 Unknown
/dev/block/mmcblk0p46 163328 163839 256 76 Unknown
/dev/block/mmcblk0p47 163841 165888 1024 47 Unknown
/dev/block/mmcblk0p48 165890 167937 1024 34 Unknown
/dev/block/mmcblk0p49 167939 170498 1280 36 Unknown
/dev/block/mmcblk0p50 170500 187901 8701 71 Unknown
/dev/block/mmcblk0p51 187903 196094 4096 48 Unknown
/dev/block/mmcblk0p52 196096 196607 256 73 Unknown
/dev/block/mmcblk0p53 196609 200702 2047 26 Unknown
/dev/block/mmcblk0p54 200704 1835006 817151+ 83 Linux
/dev/block/mmcblk0p55 1835008 3833854 999423+ 83 Linux
/dev/block/mmcblk0p56 3833856 4095998 131071+ 83 Linux
/dev/block/mmcblk0p57 4096000 4452350 178175+ 83 Linux
/dev/block/mmcblk0p58 4452352 4456446 2047+ 33 Unknown
/dev/block/mmcblk0p59 4456448 4504942 24247+ 19 Unknown
/dev/block/mmcblk0p60 4504944 4505085 71 90 Unknown

Partition table entries are not in disk order

The thing is, those extra partitions don't seem to be in use. Running mount only lists the following partitions as mounted somewhere (irrelevant mounts excluded from the output)

/dev/block/mmcblk0p25 /system ext4 ro,relatime,user_xattr,barrier=1,data=ordered 0 0
/dev/block/mmcblk0p26 /data ext4 rw,nosuid,nodev,relatime,user_xattr,barrier=1,data=ordered,noauto_da_alloc 0 0
/dev/block/mmcblk0p28 /cache ext4 rw,nosuid,nodev,relatime,user_xattr,barrier=1,data=ordered 0 0
/dev/block/mmcblk0p30 /devlog ext4 rw,nosuid,nodev,relatime,user_xattr,barrier=1,data=ordered 0 0

What are all these extra partitions for?

Is this specific to my particular device (HTC One V, with firmware for Cricket Wireless), or do all Android devices have this sheer number partitions?